Don't discount that plump aftermarket battery -- I bought one for my Pre and love it. It adds about 4mm to the dept of the thing and actually gives it a really contour in the, uh, palm. Bonus feature: No more smudgy battery cover! (Yeah, also not Touchstone, but I wasn't in love with the inductive stuff...)
Everything the AC above said -- terrific interface, great notifications, multitasking, freedom of apps-catalog choice -- it's all true. I'll grant that I was already a big fan of Matias Duarte's interface work, but the Pre just...makes sense. Damn shame the Sprint marketing campaign didn't; I've seen the more recent ad with the cute girleen shoe-shopping and wondered if things would have gone differently for the Pre if the first brand "face" had been her and not that spooky ginger lady.
Scientists will study your brain to learn more about your distant cousin, Man.