Still using a 3GS, personally - excited to upgrade regardless of whether the exterior design has changed at all. I'd love to see a different design (didn't upgrade to the 4 mostly because I hated how it looks) - but the only thing that would actually disappoint me is if Assistant isn't, in fact, coming.
Hell, if I can only launch apps and send texts with it I'll be tickled. I drive a Mustang with Sync in it and listen to Pandora radio over my iPhone - if someone calls me I can answer/talk via the cars bluetooth - but I can't get back to Pandora without looking at my phone, just being able to re-launch that or send a text message without having to look at my phone will be worth the price of the upgrade for me.