Just the price and availability and almost complete lack of true 1080p content or hardware support. But yeah, it LOOKS awesome. I wanted a 1080p TV because I wanted future-proof technology, but after months of fruitless searching, I had to give up! It just wasn't worth the extra cost and limited options. I had to "settle" for 1080i.
Molly ripped on 1080p TVs and I was deeply chagrined. My brother in law just bought my parents a 61" Samsung DLP 1080p television and it is teh awesome. Sure, 1080p plasmas are still hard to come by and expensive, but the 1080p Sammy rules. I just told a friend of mine who is looking for an HD TV that if he buys 720p now, every time he looks at his set, he's going to be disappointed.