The really compelling things for me:

html email (can you even get that on the Treo? I haven't seen it! I just got a Blackberry Pearl and you can't do it there either! WTF)
true browsing with wifi and edge. The NYT site Steve went to during the keynote looked perfect. I need that. Screw all these mobile friendly web sites - I want the real deal.
video (w/ widescreen to boot) - ok, not that compelling as I'd much prefer to watch that stuff at home, but can you YouTube on it???
form factor / wow factor - jesus, it just looks crisp

Congrats Hugo! Did you work on this?

- Jon