As someone who uses The GIMP extensively and Photoshop occasionally.. "uhm. no."
The GIMP is not even close to Photoshop yet. That's not to say it isn't a perfectly capable tool for what most people do, but then 'most people' would be fine with Elements, or Lightroom, or Instagram. Graphics professionals will have to weigh their individual demands and see whether The GIMP or one of the many plugins/scripts fills those demands in an acceptable manner.
Just as an example of what I mean by the latter, and I know it's a limited use case but this applies to so many things, content-aware rescaling.
In Photoshop you activate the tool and just scale the layer through the typical scaling interface (e.g. drag edges), and the result is shown instantaneously if your machine can handle it.
Now let's do it with The GIMP. First off, The GIMP doesn't have this feature. You'll have to grab the Liquid Rescale plugin. The main interface offers some great control, but if you just want to rescale the layer the Interactive mode sounds more promising. Except that all it does is update the layer every time you let go of the up/down control / enter a number into the fields while scaling from a fixed pivot (top left corner) While much better than going through the main plugin interface (where you have to commit, then undo if not to your liking, etc.), it's a far cry from essentially the scale tool using a different algorithm for its scaling - who knows, maybe that's on the feature list for a future version, it would certainly be a sensible place to put it.
Perhaps a bit less esoteric, adjust the canvas size, and let's say you want to add a 2mm border around the edges. First of all, you can't just say you want a 2mm border. You'll have to add 4mm to the width and height first, and then set the offset to 2mm on each axis. Great, keeps your brain accustomed to doing remedial math. So you do that and now go do it again. Notice how the unit dropdown is no longer set to mm? The reason for this is that the unit dropdowns always use the unit associated with the image (bottom left below canvas) rather than the last-used setting. Both have their merits, but % (percent) is not a unit for images, but is a common unit in the drop-downs. Similar things apply to e.g. the aspect lock button.
Some things a script-fu can address, but many things it cannot. Yes, it's open source, I can add the features (or pay somebody to add them) and with a lot of luck even get them accepted into the trunk (so I don't have to keep patching and compiling / paying somebody to do so). Can't really do that with Photoshop. But but for a long, long list of such features the fact is that with Photoshop, you don't have to to begin with.
There's plenty of reasons I dislike working with Photoshop - it's far from perfect and I like the direction The GIMP is going in - but there's many more subtle and yet aggravating things besides the ubiquitous CMYK and GUI layout arguments (two areas that are very, very low on my list - if I went into why, this comment would be even more rant-y.)