Ok, I realised we had like, a dozen of bugreports that sometimes weren't marked duplicate, and sometimes were, and not all of the problems are in the same report, so here's a copy-pasta of the important posts in all the reports:

https://bugs.kde.org/show_bug.cgi?id=349459

The reference image docker, while usable, has a very clumsy user interface, requiring several steps each time to set up images as reference. Some crucial improvements would be:
1)When hovering the cursor over the reference docker, integrate the use of zoom, rotation, mirror and panning as if it were the canvas.
2)Add the option to include and delete directories to the directory dropdown menu.
3)Add the option to change the home directory for reference images.
4)Add the option to drag and drop images to use as reference.
5)Add the option to save and load sets of images under a tag.

https://bugs.kde.org/show_bug.cgi?id=360454

Often I just need a quick reference from the web, I don't really want to download the image so I can use it with Reference docker. Think about people that go though reference quickly, they would just copy and paste the url. Well it is at least something to consider.

https://bugs.kde.org/show_bug.cgi?id=366359

It would be quite useful if Krita had functions in the Reference image Docker to allow you to easily do gesture drawing using only Krita. It should allow you to select a folder, whether it selects the image randomly or sequentially, and the amount of time for each image to remain. The image would remain for the time selected, then switch to the next image either sequentially or randomly. This would be fantastic for pose practice and the like. If you wish to do something like this currently, you need to use external software, which is not ideal.

Duplicates:

https://bugs.kde.org/show_bug.cgi?id=338807

R: the reference images panel shows CMYK jpg/jpegs in over-saturated and incorrect color. for reproduction save a CMYK jpg and browse it in reference images panel
B: That's because the references panel uses Qt to load the images, not Krita's code, so it's entirely un-color managed.

https://bugs.kde.org/show_bug.cgi?id=352085

I've been using the reference image for a couple of weeks and I've been getting slowed down by the way it works, usually I work with this workspace
https://dl.dropboxusercontent.com/u/23355517/Screenshots/overviewpanel1.png
Every time I use the reference panel I find myself using the mouse instead of the pen to work with it, the ctrl shortcut to zoom in/out is not available which force me to click on the small window that when it zooms in it does on the top left corner of the image , and since you cannot pan the image you have to move again to the part you want to need using the small bars.
The other minor complain I have is the inability to change the path of the regular folders of the images since I use different folders from the usual OS folders it gets a bit annoying to change the path each time I enter Krita. I think it could improve with something like this
https://dl.dropboxusercontent.com/u/23355517/Screenshots/overviewpanel2.png
The zoom levels on the bottom would help greatly to zoom in and out easily, and a pan shortcut like the spacebar to pan across the image would be amazing, and well the ability to change the paths would be wonderful. Sorry if it sounds so demanding or complaining but I love this feature so much and I think that it could be improved; I would like if you consider it, please

https://bugs.kde.org/show_bug.cgi?id=348872

The default folder of Reference Images docker now has to be changed every time I start Krita. It would be nice if Krita on startup loaded the last recently used folder or if there was an ability to change the folder that is loaded on Krita's startup.

https://bugs.kde.org/show_bug.cgi?id=325210

BB: Reference images docker is great but I think it strange I cannot use normal pan and zoom tools to move around the image. It would be so much quicker and intuituve then the current option where you can only drag to zoom in,and then are stuck with scrollbars and slider to move round and zoom out.
secondly would it be possible to store the links of the images you added to a .kra file? That might save time between several sessions where you wouldn't have to load each image again and again.
A: Krita dokers among its features the "Reference Images" unfortunately at each session, the program forgets the loaded image in that window. I think that also save the path to that file in the Krita document is trivial, as no one has ever thought of that? Also in respect of the management of "Doker" any variation of zoom (using the appropriate Doker bar in the reference image) the portion of the display image always starts from x=0 and y=0, while it would be more convenient and proper that the active center of the zoom was also the center of the new zoom level ... I hope I explained myself!
Also, the docker "Reference images" allows you to pick the color and I find this very useful. Unfortunately, besides the defects above mentioned, it happens that during the click to pick up the color if, without wanting, you move (even slightly) the mouse, it generates a zoom and you need to reset the zoom of docker window!
J: I just want to add my +1 to reference image paths being stored in the .kra and loaded when opened.

https://bugs.kde.org/show_bug.cgi?id=335137

Should change the icon on the zoom button to a generic magnifying glass

https://bugs.kde.org/show_bug.cgi?id=335126

zooming of images is currently towards top-left corner. It would be much better if this was implemented toward the center of the image.

https://bugs.kde.org/show_bug.cgi?id=335125

The widgets in the image docker is missing tooltips.

https://bugs.kde.org/show_bug.cgi?id=335124

Currently thumbnails are rendered as a strip. This should be implemented to scale in two dimensions, as a grid.

Reader's digest version of that:

1. The docker doesn't allow for panning and zooming using the same tools as the canvas.
2. The docker doesn't allow for adding a bookmarked folder, nor saves into the fileformat.
   1. Opinions are divided over where the saved settings should go:
      1. The kritarc?
      2. The kra?
3. The (rightclick) color picker isn't color managed, the way images are opened needs to change for that. (maybe also needs to follow the canvas input settings ir invocation)
4. Drag-and-drop of files onto the canvas
5. Gridview
6. carousel view, where the image switches randomly for gesture exersizes.
7. tagging files
   1. Can this be unified with dolphin's file-tagging or would that be mad-man's work?

The first two and the fourth are the most requested. The third is not requested often but kinda vital.

I'm agree with most of the points above but I have a couple more wishes:

1. Ability to turn ref picture grayscale.
2. Hide UI button, which will hide all buttons\slider on the docker itself. Except little "+" button on the corner which will bring UI back.
3. "Navigation sync" (or navigation link). All navigation moves (pan, zoom, mirror, rotation) done to canvas also applies to ref picture too. The idea is to make it relative, like "zoom in two steps" will 50% -> 100% for painting and 100% ->200% for ref, same for pan. This way ref picture and painting don't needs to be same size or aspect ratio. One of usecases: few portrait ref pictures and one .kra file, sync and paint one portrait, unsync, change ref and pan to other area of document, repeat.

Discussable:

4. Save ref pictures inside .kra file. Ability to move pictures from ref docker to file itself (as layer import) and visa versa. This is also very useful if share files with others, and if krita will suddenly became industry standard :)

Super-puper feature:

5. Handle multiple images at once. Select, move, scale, rotate, change opacity, mirror, crop, arrange several pictures or one by one. There is very cool program called PureRef which can do it and it very useful and easy to use (also it's free). There is a good video from Matt Kohr about this program: https://www.ctrlpaint.com/videos/a-better-way-to-use-reference-images

He didn't show all features but I think it's enough to show the idea. Krita will have 2 (at least) advantages: colorpick from refs (very cool), and ref navigation without need to change focus to another program.

I personally don't use reference docker now, but good navigation will change my opinion, don't even saying about other features.