That is one of the faster iMac G5 models. Personally the design is one of my favorites. The real issue with these is the capacitors seem to have issues (not all of them, but a lot of them). If yours is OK then you have a nice machine. Just open it up and look at them and see if they are bulging or leaking, if not you are good to go right now.
They are still very useful for web browsing (TenFourFox browser is my favorite), email, MS Office, etc. Basically most uses. The limitations are really the PowerPC processor not being supported and older versions of iTunes, etc. that may not support newer i devices if you are using devices such as the iPhone 5.
Essentially Leopard with the Mountain Leopard theme on this forum will make it feel like a new machine. All credit to AQUADock for preparing such an awesome theme.
You can do Office 2008 (still good), iTunes 10.6.3, iWork 09, iLife 09, and many other things. Essentially anything a modern PC can do your iMac can do but needs the right software. Worst case, I am sure you can sell it for at least what you paid.