Not impressed
No, the real problem in my mind is that the developers obviously expected you to keep your iPhone in the cover permanently after having slotted it in for the first time! The keyboard ads quite a lot of weight and flaps about awkwardly when you try to make a phone call. It makes it almost impossible to write a text message comfortable on the go - using the keyboard for the text message requires you to prop it up with one hand and type with the other, which makes the entire thing both much slower and much more cumbersome than using the in-build keyboard. Using the in-build keyboard on the other hand is greatly hindered by trying to keep the mobile in balance with the heavy keyboard hanging off one side.
My plan had been to just use the keyboard when I am actually looking at doing some work and otherwise taking my mobile back out. Sadly, the "taking it back out" part just took me about 5 solid minutes, including a broken nail and left my gorgeous GelaSkin positively butchered. Not something I am willing to do again, but I am neither willing to sacrifice the comfort of using my phone for the few times a day a keyboard actually speeds matters up.
The creators seemingly also assume that you only type in one language, which seems an awkward choice considering how easy it is to switch keyboards on the iPhone. I bought the QUWERTZ keyboard, as all my other keyboards are QUWERTZ and I find it easier to type on a familiar key set up. On the others I am however still capable of writing in both English and Japanese without having to memorize a different keyboard layout! Sadly not on this one. As soon as I switch to a language that isn't German (which I do multiple times a day), I better remember where all the keys are on the appropriate language keyboard, because those are the letters I will get if I press the key. I might be able to fix this point by poking around in the settings of my phone, but it is still really unintuitive for a phone as multilingual as the iPhone.
I am still giving two stars because the keyboard works and is reasonably comfortable and you can take it out of the awkward case, which means I will from now on be carrying it about separately. However that really kills the original concept of being able to conveniently prop the screen up while typing on a desk. On the whole I am really not impressed though.