If you're confident you can complete the rooting process and like tweaking things in your phone, do it. You can get ROMs that are basically stock with some superuser powers.
JUST REMEMBER THAT ROOTING VOIDS YOUR WARRANTY.
You can overclock to increase cpu performance or underclock to increase battery performance, or utilize both.
You can tether your phone to your computer for anywhere (with a data signal) laptop access to the internet.
You can customize just about anything
You can adjust how android handles its internal processes
You can use ROMs that don't use sense or just use the social networking aspects of sense
You can get live wallpapers
You can use JIT (what makes 2.2 so much faster than 2.1), although JIT is pretty fenicky (sp?) with some apps that utilize the data network for streaming, such as pandora
You can always unroot if you don't like all that root has to offer, or if you encounter a bug and need a stock phone to return to the big V.
And that list just scratches the surface. I for one love messing around with my phone, and the performance benefits have made my phone much more usable (less lag mostly the issue, especially with the dialer).