There are really just two things that make the Samsung Stratosphere worth looking at: the 5-row physical QWERTY keyboard, and Verizon's 4G LTE. Aside from those two elements it's decidedly mid-range, but if you covet those things here's the nitty-gritty.
They keyboard isn't bad at all. They keys are pretty small, and the layout will take a bit of getting used to, but the keys have just the right amount of click to them which means that with a little practice you'll be able to type without looking (much). That's one of those forgotten beautiful things. Who among us would use a keyboard on our laptops that we couldn't type on without looking? I would like to have seen the keys raised just a bit more as they are extremely flat, but at least they're spaced-out nicely, and I liked the dedicated numbers row.
As for the other main ingredient, it's Verizon 4G LTE. It's awesome. It's the fastest and best 4G out there, hands down, assuming you're in one of their rapidly expanding coverage areas. There's not much to not-like there except that LTE is a voracious devourer of batteries. To compensate, they stuffed in a 1800mA battery, which is way heftier than you find on most 4G smartphones (the high-end Droid Bionic has a 1735mAh battery and that's larger than most).
To squeeze all that stuff in they had to make the device very thick and it will cause a noticeable bulge in your pocket. Its body is light plastic which makes it feel pretty cheap. It's got the same Super AMOLED WVGA screen and 1GHz Hummingbird processor that was standard about a year ago, and it's only got a half gig of RAM. This is not a phone for spec-hungry power-users. If anything it's for business users who need to bang out emails and download large PowerPoint presentations in a hurry, and who don't care about HD gaming at all. It's one of Samsung's "S.A.F.E." (Samsung Approved For Enterprise) devices, which means it's more ready for business usage with enhanced security compared stock Android phones. It runs Android 2.3 (Gingerbread), and it'll run you $150 on-contract. If you're on Verizon and you must have a keyboard (and some must), it's between this and the Motorola Droid 3. The Droid 3 has a dual-core processor and it's a world phone, but the Stratosphere has 4G LTE. The choice is yours.