We've got the black 1/2 leather sports seats and they seem fine, the leather feels a little thinner than I'd prefer and only time will tell how it wears (won't be my problem though cos it'll hopefully be traded in for an CooperS or and Alpina before that bothers me !)
Overall though the seats are quite good, if a little unsupportive
I've got the full leather sports seats and find they are comfortable and give a good driving position for me. The dealer I bought my car from recommended going for sports seats if you want leather upholstery though - he said the leather fits better/more snugly. When he showed me the difference between the standard and sports seats with leather, I could see his point. Admittedly, I don't really find the lumber support does much for me
I have all cloth sports seats - they were only available from December build. They are very firm but comfortable and grip you better than the standard seats. Having said that, i have had sports seats that gripped you even more. The quality of the cloth covering seems excellent - but I've only had the car since the 2nd Jan, so you wouldn't expect signs of wear! The standard sports seats don't come with lumbar adjustment, but don't seem any the worse for it.