newbie here that have some question to ask about rooting

after i root the device, i lost sense UI, which means?
without the senseUI, anything special?

whats the major advantages to root/ not to root?
(means like after rooted my device than i cannot update from HTC website like jailbreaked iphone)

curios abt another question

it worth to buy ap set now or wait for official launch on retail set?

My thoughts about micro sim is that apple just wanna to start another format war
juz like iphone started with no flash, bluetooth etc that most of us think is essentials
if 70%of current user migrate to iphone 4g, and telco will NEED to do upgrade lo