I personally use a Wacom Bamboo Pen & Touch and I can say that it is really great, I mean in every aspect it is great as a tablet. As a Touch pad however is another matter, it does come in handy often in photoshop or w/e but it is somewhat difficult to use because you have to really really REALLY overdo the motion.
Say when you rotate the picture you do it in the same way as you would on a smartphone or whatever but you really need to twist your wrist if you want input :P
If you want something a bit more flashy I suggest an Intuos because if I am not mistaken you get to see everything on the screen on the tablet aswell, it works as a secondary display. Just buy anything Wacom basically and you will be fine.