I have this case, but I prefer to use the original Siemens case, for the sole reason of ergonomics.
The Blue Angel is a sleek, sexy piece of art (all compacted into a phone), and to hide it in a bulky titanium case just doesn't seem right to me. Also, you cant use the touch screen and using the call/end and D-Pad buttons is a clumsy task with the innopocket case. I'd recommend getting a nice leather folder type case or an OEM style Siemens case.
However, the Innopocket case is GREAT when you use the phone as a GPS. Just attach the car mount to the back, and it protects the phone from hitting the windshield and dashboard while driving down a bumpy road.