After months of waiting and no small amount of whining from yours truly, Sony has finally seen fit to grace the United States with the presence of its oddball folding tablet, the Tablet P. For better or worse it’s only available on AT&T’s wireless network. Sony fans and those looking for a little something different have been waiting a long time for the Tablet P. Does the unique folding screen mechanism make for a better tablet, or yet another Android oddity? Let’s find out.

The folding 10-inch clamshell is undeniably striking: we can say without exaggeration that there’s nothing quite like it on the market. The Tablet P uses two identical 1024×480 screens, which can operate compatible apps independently or combine them for a full 1024×960 screen, nearly a full square. The experience takes some getting used to, even if you’re used to Android’s tablet interface, but after a few minutes any technically-minded person should be able to get around with minimal difficulty.

The Tablet P’s curved sides make maximum use of its internal space, cramming a Tegra 2 dual-core processor, 1GB of RAM and a 3,080mAh battery into the casing. It’s an attractive design made all the more interesting from a lack of boxy edges, and will slide into a (large) pocket or bag better than any 9 or 10-inch tablet currently on the market. The processor and RAM are more than enough to make Honeycomb zip, though it’s not the smoothest experience we’ve seen. This may be due to some “enhancements” to Android 3.2 on Sony’s part.

Unfortunately there’s no room for more than 4GB of storage space (though you do get a 2GB MicroSD card gratis) or 4G LTE – you’ll have to make due with HSPA+ “4G”, something of a penance considering the $399 on-contract price tag. Sony has already committed to an Ice Cream Sandwich upgrade, but between the manufacturer and the carrier it could be quite some time before it materializes.

If you live in Sony’s entertainment world, you’ll appreciate the various included software: the PlayStation store for access to converted PSX titles and other games, plus Sony’s music and movie stores. Of course with access to Google apps and the Android Market, there’s no reason to limit yourself, either. And speaking of software, Sony says that more than 40 third-party apps take advantage of the Tablet P’s unique dual-screen design, including Evernote and News 360.

Build quality is rock-solid and typical of Sony. Those worrying about the moving parts in the hinge needn’t bother. The screen is surprisingly glossy, though; while LCDs are generally better than AMOLED screens at blocking reflection, the coating on the inside of the tablet seems to reflect a lot more light than most. The volume and power buttons on the side of the tablet are tricky, and we wish that it had a MicroUSB charging port instead of the proprietary one sitting on the side, begging you to bring along a second adapter.

You can pick up the Sony Tablet P today from AT&T for $399.99, on a two-year contract or extension. We’ll have a full review up later this week, but check out the unboxing video below in the meantime.