I don't care about the battery. I love the phone's dimensions, having determined I would not want anything bigger. One thing the dimensions have done, as I see it, is create a massive aftermarket of cases that fit without becoming too big. I think if you ran this query among case designers they'd scream NO THICKER. Maybe I'm off, but that's my perception coming from a Razr Maxx HD market that wasn't exactly bustling. Perhaps this flood of options isn't so much the good starting point, rather it's typical for Samsung devices?
That said, front facing speakers would be slick. (But, again, I wouldn't want the footprint to change.)
HTC's theme editor would be cool, but I don't mind checking the store for new, free themes every week, even if they do draw the ire of many forumites.
#1 thing to change, no ifs, ands or buts.... the headset. Awful. Who wears buds like that? Ugh. I could leave 5 sets of headphones laying out and I think these are so bad that the dog would chew only the other 4 cords.