I got a Thunderbolt, its my first Android phone and I love it. I've been planning on eventually rooting it but just thought I'd stick with the default setup at first.
A recent HTC update has started giving me some random reboots making me think of trying a custom ROM that might be more stable. I'd want to make sure I can reload the original OS if I need to take this think back to Verizon.
Root would be cool if I could get rid of some of this bloatware and make the thing a bit zippier. I'm not sure exactly what other benefits I'd use from root though.