"Great upgrade to the Blackjack series."4.5 starson by lilsim89
Pros: Great looking, VERY fast performance, picks up GPS signals relatively quickly, slightly improved keyboard, slim and aesthetic, no cheap looking metallic band like the BJ2, call quality is above-average.
Cons: Slippery, proprietary ports, must remove battery to add or remove SD card, speakerphone should be a little louder, screen doesn't compete AT ALL with Blackberry Bold.
Summary: My phone lineage recently? Blackjack, Blackjack 2, Jack. The Blackjack 2 was not a real upgrade over the original BJ, more of a refresher, and not even a good one at that! It didn't fit as well in the hand, and the cheap metallic band on the exterior wasn't a nice touch at all. I appreciated the GPS, though where in the world was WIFI?
The Jack is a BIG improvement over the BJ series. Not only does it comfortably in the hand, it is also built sturdier than the BJ2 (Gone is the ridiculous jog-dial.) Although WM6.1 was available for the BJ2, the Jack seems much more well-integrated and polished. I must say, though, that I don't like the standard "slider" theme on the Jack. I like my home screen simple and elegant, so I made my own and love it.
Performance on the phone is HUGELY improved. Gone is the lag between button presses and action. One benchmark that sums it all up is my Garmin GPS app for the phone. On the BJ2, it used to take nearly 10-20 seconds to (re)calculate a route, now it is almost instantaneous. Oddly enough, though, start-up time doesn't seem to have improved much.
HSDPA (3.5G) is freakin' fast and generally stays well connected in my So. Cal. city. I wouldn't even care for WiFi if the 3.5G service was 100% reliable. As for the shipped browser, I've never liked Internet Explorer (clunky describes it well) so I recommend buying Opera Mobile, it's MUCH better, though not as configurable as I'd like it to be.
One of a few gripes of mine is that the power button must be used to wake up a locked phone, and it isn't as convenient as using the END button- something that gets annoying over time. Also, AT&T clutters the program menu supremely, like always. If you're an advanced user, I'd invest some time in cleaning that up. Though it requires that you "app unlock" your device (not the same as carrier-unlock), it's well worth it if you value your sanity.
Overall, money well spent. (And not that much of it!)