Bought a battery on the recommendation of this thread and cant say i personally got any greater battery life out of the battery. The battery does stick out but not noticeably and putting the cover back on is reasonably easy. As a replacement battery, don't expect anymore than stock, but at £5 its not bad.
In battery monitor widget (great app!) the battery registered at 1230Mah, although this might just be because it is hardwired in as people have said.