Chris was much better, my favourite infact, for me he was a combination of all the past Doctors.
This will be good for the show, its getting a bit stale and with Stephen Moffat taking over (who is much much better than that hack RTD) and having a new Doctor they can make it feel fresh.
Would be nice if we had a new Doctor half way through the fifth series to shake things up a bit, not that I have anything against Tennant but a show like this has always been about changing things every 5 years or so.