Darkwarrior is correct, rooting can be fraught with headaches. Corrupted sd cards, bootloops, hanging X's. READ and backup all including sd card.
I have been rooted on an N1 for a year. Most people did the N1 root cause it gave features like FM Radio, 720p recording, and some extra tweeks. CM7 is now running GB 2.3.3 as well as MIUI-Dev.
That said, I don't see the need to root the MT4g. My son is using mine as I kept the N1. But, I like sense and have a Desire HD rom from MicroMod I use on occasion and love it.
I think batery life sucks on all the hi-res screens. Although, I run everything all the time. Wifi, BT, Max Screen Brightness.
My son really likes the MT4g and has no interest in rooting. But, spend a month reading the XDA forum threads in the Android Dev section. Cyanogen/Rodriguez/etc. It will give you a better feel for pros/cons.
Enjoy your MT4g
Ken
@aysiu,
Why would you buy a phone you hate--did you not research and test it in store several times?
My son really likes the MT4g and has no interest in rooting.