I was inspired by @patrickballeux 's Ubuntu card and the conversation sparked there. Gimp is an open source photo editing program that has improved so much over the years. It's strong enough to compete with Photoshop, in my opinion.
Here is, a pro and cons list of going open source:
1. GIMP is free!
That's the beauty of open source. The new Adobe Photoshop CC costs at least $240/yr (yes, they changed this!) Or you can get the older creative suit for three times that price (which I notice is hard to get now, ever since they switched to Creative Cloud).
2. GIMP takes up minimal space (and is portable!)
With Photoshop, you need a minimum of 2.5 GB (Windows) or 3.2 GB (Mac) available in you hard drive. With GIMP you just need 200 megs. Big difference! Also, you can even run on a flash drive to run on any computer.
3. GIMP is cross-platform
You can use it on Windows, Mac, and Linux. Photoshop isn't available for Linux at the moment.
1. Photoshop is the industry standard
If you're a professional, most likely you know that many printers accept .psd files and .eps...both from Adobe.
2. UI can get confusing
Not to best UI when comparing it to photoshop. But, there are things like Gimpshop that give your GIMP a photoshop-like UI. (Check it out here: http://www.gimpshop.com/)
3. Less features
Has less features, but some GIMP features are really useful...such as scripting. Plus, there are many plug-ins created by the community that you can use.
These are just some reasons to go open-source. Any other people have some more?