I really want to use LauncherPro, mainly because I like the Nexus One look, but I have a few niggles -
The Glass Bar at the bottom (that the N1 and HelixLauncher have) needs adding, I really like that, and the menu needs to be changed to look like the Helix and N1 menus do.
I know it's two really stupid thing but it bugs me as I think not having them detracts from the clean Android look
I also do quite like some of the Sense UI widgets, I know most can be replaced but many aren't as polished.
Try HelixLauncher2 from the Marketplace if you want to see what I mean, it's not quite as smooth as LauncherPro and lacks a couple of bits, but aesthetically, it's far nicer imo (aside from the zooming effect when you open applications that LauncherPro has)!
Here's hoping the LauncherPro guy will add it, although it won't really be necessary when Froyo is all set for the Desire (from Paul), hopefully next week!