GIMP

They'll have 1 thing in common - they all got used to Photoshop first.

GIMP isn't perfect. It's got rough edges. It is developed by volunteers, it is not backed by a huge commercial effort like Photoshop nor is it sold for a huge price tag.

Considering that, for 98% of image editing requirements GIMP is just as good as Photoshop. Only if you are in an elite upper tier of artists would it actually be inadequate.

If you are used to Photoshop, you'll find GIMP horrible to use. The same is true in reverse. They are difficult applications with different structures and different approaches to many tasks. It's like going from a Mac to Windows and vice versa. You have to unlearn what you know and relearn something else, and for many that is too much to ask.

However to lack the perspective to understand this basic principle - that you prefer what you know - and lay into the work of the GIMP developers with very unconstructive criticisms is hardly helping anybody. Given it is open source, why not engage them, or why not try to implement improvements? Oh, that would take effort. Trolling online takes no effort whatsoever!

The GIMP has a ton of great features, is constantly improving, and is never going to cost you money. It will just cost you a bit of your time to learn how to use it.

I use GIMP professionally at my job. We use only open source software, so I had to learn GIMP instead of Photoshop. There was a pretty steep learning curve, but I will never touch Photoshop today. I still miss some things like layer effects though, but I think GIMP wins in the end. I know it is a bit different and frustrating to get a grip on. I believe that everyone should give GIMP a honest try before thowing it into the trash can.

You will be amazed how awesome this software is. A lot of premium features simillar to phtoshop. ut it's totally free. So you can enjoy all this functionality and not pay money.

G'MIC is a must have free plug-in suite.

While GIMP lacks much of the polish of Adobe Photoshop it is in every man's budget and ought be installed on every desktop with or without photoshop.

GIMP is rumored to be expanding layer blend modes.

Adobe has repeatedly ignored requests to add this functionality to their SDK.

I've just recently installed the new version of GIMP - 2.8, and I already love it. The previous 2.6 did what I wanted anyway. But this one does even more and in much smoother convenient way. 10 out of 10. Who needs to pay hundreds of bucks for PS now (except for those involved in professional pre-print routine)?

I use it in Windows and Linux and it works pretty much the same in either environment.