I've got the 55" model. I'm thrilled (of course) with the HD picture, but I do have a couple beefs:
1) Only one wideband component video input. I can't hook up my progressive DVD player to the TV if I have my HDTV tuner hooked up.
2) No discrete power/switching codes available for my Pronto.
On the plus side, their service seems to be pretty good. I couldn't get the picture converged properly with the user convergence menu, so they sent a service guy out and I peeked over his shoulder, so if anyone wants the service convergence controls, PM me or reply in this thread and I'll send them or post them. I've been able to tweak the settings for both the HD and NTSC inputs.
I also like having the VGA input around back. Haven't used it much, but it's cool!
Finally, the thing that sold me on the Samsung at the store was the front input jack panel. Push a button on the front of the set, and a panel slides down to reveal the inputs and front panel menu controls. OK, I'm a dork
Now if only I could get more than just HDnet...