I just upgraded my G2 using this method and worked like a charm!! Easy as pie and running gingerbread smooth as silk...my favorite features:
-BLACK notification bar..call me crazy but black background on notification bar FTW!!
-LOVE the 3G/4G indicator..the "H" always had me guessing
-my battery life is incredible! Had a full charge right at the update at 7:00 pm..send plenty of texts, bout 20 min of web and 3 phone calls @ roughly 10-15 min apiece with wifi running the entire time and @ 90% battery at 1:30 am!
-the battery icon in the notif bar is now vertical and prof looking as opposed to the horiz cartoony (imo) batt icon that was the 2.2 stock
-Above all my G2 is running smooth as silk! no lag, no overheating, like i just bought it with gingerbread installed!
Personally if your not rooted, I'd go for it! Worst case scenario youre left with an (95%) official update without all the TMO bloatware (which Im assuming would be the remaining 5% lol)..btw my G2 was totally stock with a full factory reset before trying this..updates own personal reset did the trick for me, no problems whatsoever yet! KUDOS!!!