I bought one already and its more for a spare battery then anything else. I don't care for larger batteries which require a new door and make the phone bigger. I would rather carry an extra battery when needed and 1600 should give you about 15% more battery life then the stock bat.
HERE is a discussion on this already but I noticed when you look on the website it states the battery is for the TBolt and the My TOUCH 4G. So are there extended batteries for the My TOUCH 4G that will fit the TBolt? Are they compatible?