I am very anti-gimp. LOL.
Gimp lacks many obvious features which it really should have. My biggest gripe is it lacks adjustment layers, which makes editing extremely inefficient. All edits are destructive, which means to get similar function you have to duplicate the layer, apply the adjustment and mask in/out the areas which you want the adjustment to affect. That means for every nondestructive adjustment, you must add a color version and to make it a local, a greyscale mask, whereas in applications that offer this feature a single greyscale layer is needed. This can start adding up - if GIMP allowed 16-bit images. Which it doesn't. Because GIMP only permits 8-bit editing, your files are much less flexible and will be more prone to banding and noise. If you plan on always shooting JPEG, then you won't need 16-bit support. If you shoot RAW and export a 16-bit tiff, you will.
Gimp also does not support CMYK, it will allow you to decompose CMYK channels - which seems like a good idea, but is really pretty worthless for prepress, something you prob. won't need. Gimp also has incomplete and awkward color management, though this has improved in recent versions. Gimp's Hue/Sat tool, which is one of my favorite tools is really pretty gimpy, and it's impossible to pinpoint an exact color, even photoshop's feathering in hue/sat I wish were a bit more robust.
Photoshop I do think is bloated and is missing some features I wish it had. It's overpriced and Adobe themselves are obnoxious and don't listen well to customer demands. For example, it took forever before they put a histogram in the curves window, something I remember people wishing they had back in version 5.5.
One less expensive alternative to Photoshop is Photoline32, which does most everything photoshop does (or at least that you'd need) and a few things it doesn't. I've found it's not the best for prepress, but since you're just starting out with photography then you prob. don't care about that. It has a full featured demo available for download.
Some of Photoline's handling of layers can be kind of strange, and it's UI takes some getting used to, but I have been pretty impressed by it and have been using it for a few years now.