Rooting voids your warranty. Installation of new roms to replace what you have, you do at your own risk. If you go with cutting-edge features in one area, you may be sacrificing your basic features in other areas.
Go to this area -
Captivate - All Things Root - Android Forums
Look especially at the top "sticky" link (it's stuck in one position so you can always find it).
Look over the successes and failures reported there, ask your root questions there, make your own wise decision.
You'll find a lot of controversy on whether rooting is ok - both sides of the issue present 100% valid arguments, in my personal opinion.
And most importantly, this message from our sponsors and me:
Welcome to the forums! Take a moment to check out the info in my sig, at least below the Latin part.
PS to the parties feeling very strongly about whether rooting is a good thing or not -
The discussion to root or not tends to consume many threads. If users here are amenable to it, I'll gladly entertain a thread devoted solely to presenting both sides of the argument - a fully moderated, usually-locked thread - just presenting the two sides clearly, because the pro and con of this doesn't really change. I'd then be willing to add it to the appropriate sticky post so you can all reference the link.
I'm just putting that out there because I gotta believe many of you must be tired of typing the same arguments out for each newcomer asking the question.
It's up to you, gang.
PPS - OK to start a new thread on this or PM me for questions.