Just curious as to your opinions.
GIMP is a lot better than it used to be (for Windows at least), but I would still stop short of calling it the Blender of the 2D world (though there’s no reason to not try it considering it’s free).
A hint though; If you are to use GIMP, the G’MIC plugin suite is a must if you want to do any serious post-processing work (some powerful tools in there).
You can’t compare 2d software with 3d ,3d its much complex ,
But yes I think gimp are very powerful 2d program
Blender+gimp =the dark night of all programs 
If you are looking for good OpenSource softwares for image editing/manipulation and painting, just say that GIMP and Krita are two good alternatives that you are free to try and use. Enjoy all of them!
I use both GIMP and Krita. Whilst both 2D, Krita is more the art, whilst GIMP is the process. I simply choose the best for the job in hand.
No 2D application can come remotely close to the capabilities of blender. Even in the case of Photoshop. 2d apps are made with a very specific workflow in mind but even though they are much easier and streamlined to use for 2d , when it comes to features a 3d app will destroy any 2d app.
3d graphics are by themselves quite demanding in technical requirements and because its the nature of 3d to output 2d as its final format even in the case of game engines, having extremely powerful 2d orientated features is a must have.
But the story does not end here because any 3d feature can easily have application to 2d stills and 2d animations alike.
Of course Blender comes with 2d orientated features and tools like freestyler, compositor, curvers, image editor etc but they are just the tip of the iceberg
The issue with Blender is that some things are plain easier to do in 2d apps like Photoshop and Gimp. But if you build a solid workflow from practice you can be much more efficient than those apps. You will rarely see people do that because of the very steep learning curve of 3d graphics but there are many 2d artist that rely a lot on 3d apps or even use 3d apps exclusively.
In the end its up to the artist and the way he or she likes to work.
So to summarise, Gimp is not the Blender of 2D world, Blender is the Blender of the 2D world.
There’s also the grease-pencil object being worked on in 2.8, and right now has been getting enough functionality to allow one to make actual cartoons (the visuals at least). Blender also brings the advantage of allowing one to position the 2D objects in a 3D space (so perspective and parallax becomes an easy job).
It’s probably not going to dethrone ToonBoom studio, but I believe it has more than the GIMP can do (animation tech.).
Nah, Moho is the Blender of the 2D world, well, not really since its not free, but if it was, it would be, no doubt about it! 
I like Krita, Gimp stil gives me the heebie jeebies!
Affinity Photo is very nicely priced and you have to pay only once, unlike Adobe products. It’s what I’ve been using instead of Photoshop for a while now for image manipulation. Gimp is more extendable though. Krita is also better for painting.
I don’t know if GIMP is the Blender of the 2D world, but Blender is definitely the gimp of the 3D world.
GIMP is the blender of 2D but only of you’re talking about blender before the era of version 2.5…
I agree with Kilon,
I use Blender for nearly all of my Creative work (besides LMMS for music, and Cinelerra & ffmpeg for sound and video editing).
It is much easier to use one program (and become extremely productive), than to use many ---- especially if the others are “clunky”.
I like GIMP as a PhotoShop replacement. Sometimes it takes a little coaching, but it’s always been able to do what I need it to.
In that way, I suppose it’s like Blender.
GIMP starts out as a single window now (no more floating messes), and the Partha builds come with G’MIC out of the box (the first part alone was enough for me to get into it more).
Gimp isn’t the worst open source 2d graphics editor that is currently being developed. Name one open source 3d editor that is actively being developed that is worse than Blender. Hell, name one open source 3d modeler. Googling “open source 3d modeling software” turns up Blender, FreeCAD, a mention of FreeCAD, MakeHuman, SketchUp(sic), A mention of Blender, Another mention of blender, a mention of FreeCAD and Blender, A mention of Wings3D, and a final mention of Blender.
The question is too vague to obtain a coherent answer.
About which 2D World are you talking ?
Photo editing, Compositing, Painting, 2D animation
Blender is often mentioned as the FOSS 3D software. It is simply because Blender touches a wider and more popular domain than other pertinent 3D apps.
But it is not the most pertinent choice as a CAD 3D software, for example.
Of course, you may like mechanical branch and need BlenderCAM.
But at least, you should try FreeCAD and BRL-CAD if you are interested in those domain.
It is not the most pertinent choice to manage 3D point clouds and meshes from 3D scans. You should try Meshlab for that.
Was Gimp as often mentioned as Blender when question was reduced to “2D+FOSS” ? Yes.
Is it still the case ? No. Why ? Because several years ago, several 2D software were not as good as they are now (Krita) or were not there (OpenToonz,Darktable…).
Is it a bad thing for FOSS World ? No. People using FOSS software are more numerous and just getting used to search dedicated apps for dedicated tasks.
Is it a bad thing for Gimp ? No. People using a specific FOSS app may still need a generalist app for wider projects and use Gimp.
K3D, Wings.
Didn’t even have to google anything, this just off the top of my head.
Lines are blurring between 2D & 3D.
Lately is getting more about intent (final product) & functionalities to get you there (workflow).
GIMP, for starters should be node based (non-destructible) to start coming closer.
Then mix in 3D canvas, Inkscape, Natron, Krita, Verve, Awesome Bump, Story Boarder…
Specifically, make it photo based (from reality to virtuality: camera raw or blank canvas to) texture editor (draw, paint & composite; filter, denoise & CC…animate…) app & you made it.
But it’s not.
K3D’s site hasn’t been updated since 15 and wings since 16.
And I’m pretty sure OpenToonz is the Blender of the 2D world.