I ordered one shortly after buying my SP2 last month and it's served me well. Like GoodBytes said, it is designed for the original Surface RT's USB port placement so on newer model Surface tablets it will cover the volume-down button, but it's not awful. You can always turn the volume down from the screen itself.
I find it very handy when turning my SP2 into a desktop - with the Bidl inserted, I can add on a mouse, DVD drive and external storage. I find this useful for when I'm installing PC games and the like onto my Surface.
Of course, the same can be done with the Surface Pro 2 Docking Station, but those are rare as a silver Yu-Gi-Oh! card these days and can only be found on
eBay... although I am starting to become
severely tempted to shell out just that little bit extra for one...
But in summary, this little device is perfect for turning your SP2 into a desktop when on-the-go. Even if I do buy a Docking Station, that will remain firmly at home. Should I need more ports, I can bring this handy little pocket-sized device with me wherever I go, along with whatever I'd need to plug into it.