To root or not to root depends on two things.
1. Do you consider yourself a tech savy "Power User"? If you don't, you may want to stay stock and be safe. Messing around behind the curtain can really mess up your phone. As long as you stay away from the radio, however, someone on this forum can help you recover from just about anything. If you do, the benifits are many. You can take off some of the "Bloat Ware" that gets in the way. You can run apps that require root that are really very useful, like Titanium Backup and Theft Aware, as well as Root Explorer. By far the most useful reason is for the "Nandroid Backup" you can run from a custom recovery. This basically copies literally everything on your phone and saves it, so at any point in time you can recover to that state.
2. You can truly make your phone yours. You can change the splash screen you see when you turn it on, you can change the animation while it's booting, you can run a custom ROM (Sense or Stock Android), you can even change kernel which affect how fast the processor runs (Overclock it to 1.2 G for example) or even undervolt it to save battery life. Point being if HTC sells 5 million of these phones, none of them will be anything like yours.
If none of that made sense or doesn't interest you, this phone will be a beast out of the box and you should let it be. If it does peak your interest, start reading through some ROM's and Hacks sections of several established HTC phones (DInc, Evo, G2) to get an idea what you're in for and ask a lot of questions if you don't understand.