Stephen Hackett says that LTE is his favorite feature of the new iPhone 5:
LTE seems impossible to me. I'm consistently seeing speeds around town better 20 and 40 Mbps down, with 10-15 up. That's a good bit faster than my U-Verse at home.
In other words, the cell phone in my pocket has a considerbaly faster than my home Internet connection.
I know many Android users have known this for a while, but holy cow, I don't ever want to go back to 3G.
I haven't done any speed tests, but anecdotally I can attest to LTE being crazy fast. I use LTE on an AT&T iPad 3, and I wonder why it took me so long to enable it. It really is great; much faster than my home Wi-Fi network. Where I live in the Bay Area, I'm fortunate in that AT&T's LTE network is widespread and fast.
I like Stephen's suggestion that Apple allow tasks in iOS be done over LTE. I'd love to be able to, say, back up to iCloud over LTE. It'd be great for updating larger apps like Pages and iPhoto as well.