The Vita TV certainly fulfills a niche role, but the crux of the Engadget review is that while the product is quiet and unassuming, it doesn't do well to instill a need in users. If you really want to play PS VIta games on your TV with a DualShock 3 controller, then it's a rather expensive means to that end – and if the game uses touch controls, you've got even bigger problems.
The PlayStation Vita TV is easy to use thanks to the identical interface and software borrowed from the PS Vita itself, so PS Vita owners will find little difficulty making the transition. As it stands, however, there isn't much reason to consider that transition.
The PlayStation Vita TV is currently only available in Japan and, on its own, costs 10,000 yen ($96). Sony has not announced any plans to launch the Vita TV outside of Japan.