I purchased the C-Berry TFT through another dealer and am very happy for the purpose. Bright and sharp picture. However, the resolution of 320x240 for a GUI is not useful. Then you should go towards 7 "with resolution 1024 (and also external power supply).
For the Raspberry PI2 Admatec has confirmed to me via e-mail that there will be drivers. At present, the picture is just mushy.