Pros: Killer combination of touch screen, optical mouse, and QWERTY board; Improved battery life vs Blackjack II; Lightweight; 3G and WiFi
Cons: Windows Mobile is Windows Mobile; Thicker than Blackjack; Proprietary headphone jack

I'm gonna catch heat from HTC fans for this, I know, but Samsung's Epix is the best Windows Mobile Professional device currently available on a US Carrier - particularly so if your main interest is in getting things done.  A lot of this assessment hinges on the fact that I personally LOVE Epix' optical mouse.  You might not, and that's fine.  But for me the optical mouse makes clicking on tiny little Web links and buttons much easier than mashing repeatedly on the touchscreen with a thumbnail or (heaven forbid) reaching for the stylus.

Windows Mobile 6.1 Pro is kind of a pain in the neck, and it definitely caused me some frustrations during testing, but my Epix loaner didn't crash or even really choke on the OS like its predecessors (Blackjack and BJ II) did when I checked them out long ago.  Epix doesn't feature a fancy UI like HTC's TouchFlo 3D or even Sammy's own TouchWiz, but Samsung did some subtle dressing up to the WM interfaces in certain areas like the camera app.

You might bemoan Samsung's move from the ultra-slim Blackjack to the relatively chubby Epix, but Epix' light weight, solid battery life,  and usability innovations offset the extra thickness in my book.  The touchscreen is good, the optical mouse is great, and the QWERTY board is solid (if not quite on par with the best that RIM and HTC have to offer).  Throw in AT&T's 3G network, a WiFi radio, and a bunch of multimedia add-ons and you've got yourself a spot-on Windows Mobile workhorse.  Just make sure you ditch Internet Explorer in favor of Opera Mobile or Skyfire.

Verdict: Big Thumbs Up