Flip 3D is a poor man's alt-tab, as we all discovered through Windows Vista, and it isn't exceedingly touch-friendly. After an initial play, you'll not touch this again.
You'll want rotation lock turned on, and you should leave it there — although the screen can auto-rotate to match the orientation of the slate, it blanks out for an exceedingly long time before reappearing in the proper orientation.
The virtual keyboard button is a nice idea: wherever you are, press it and a keyboard pops up onscreen. Execution is poor, though — unlike the usual Windows keyboard, this one isn't resizable or movable, and takes up half the screen. With the low vertical resolution of 800-pixels suddenly halved to 400-pixels, there's a good chance that the box you were typing into will be hidden, or at least difficult to navigate to. Stick to the pop-up soft keyboard that Windows supplies by default, and all will be fine.
Using the included leather case, the Eee Slate can be propped up at slight vertical or horizontal angles, as well as something that positions it more like a laptop screen, something incredibly handy given the bundled Bluetooth keyboard. A Bluetooth mouse isn't included, though, leaving the full laptop transformation just out of grasp. Synching the Bluetooth keyboard to the Eee Slate for the first time is an absolute pain, although this is the fault of Microsoft rather than Asus.
Using just the Slate without the keyboard was a mixed experience. While Windows 7 is significantly better than its predecessors in regards to touch interaction, there are still frustrating elements, like difficult to resize windows and absolutely no way to interact when faced with the boot options screen. Still, we loved the power, flexibility and portability it gave us, with even typing on the virtual keyboard a pleasant experience.
Running Intel HD graphics means this thing isn't the most powerful kid on the block, with a 3DMark06 score of 1060. It should be fine for casual gaming, but don't expect to run a recent AAA title. PCMark05 gave back a more impressive score of 4311, which positions this as a great business machine.
Turning off all power saving features, setting screen brightness to maximum and playing back an XViD file full-screen is a rather tough battery test, and the Eee Slate did quite well, lasting two hours and 27 minutes. This is roughly on-par with performance from a $1500 15-inch laptop. Lighter use and an aggressive power plan should see this extend considerably.
We've had reservations about Windows 7 as a touch OS ever since Microsoft announced it; however, the Eee Slate EP121 goes some way to alleviating those. It'll likely take Windows 8 to go all the way, and by then, it may be too late. Until then, the Eee Slate EP121 is the best Windows tablet you can get.