Well after messing with Ubuntu for a while, I finally picked up a G5 for next to nothing but it has the CS4 Suite on it so that was a major plus for me. Sure there are programs no longer supporting the PowerPC but for what I need to do it is rock solid and it didn't take long to get used to the mouse/kb combo.
First I found that having used Ubuntu, there was a bit less of a learning curve I guess. For $200 I got a machine well capable of running Photoshop and Dreamweaver effortlessly. As for what I like better, it seams faster even though it is four years old and I find the Apple environment very easy on the eyes. There is a softness that just makes working on the machine all day less tiring. This from one full day of use!
There are a few things that are no longer supported regarding the PowerPC architecture, hence the low cost for what really is an extremely powerful machine. Flash as well as many browsers are no longer supporting it but I run Safari and am happy with it. The older Flash player runs most of what I want.
Drawback, cant' stream Netflix as they only support the Intel architecture so there are some things that may limit you although, using Ubuntu and Linux, you run into some of the same issues.
For a couple of hundred bucks it is worth it I think. Plans are in place to start saving up for a used Intel architecture machine over the next year.