Matt Smith started superbly... but that's it. If he'd built on how well he started he might be an easy best by now, but as it is I'd put him just above the middle of the 11, good but not competing for first place ( Tom or Troughton) or even 2nd tier (Hartnell, Eccleston). He's in there with Davison, Tennant and McGann for me.
Yeah, if they followed the route series 5 led and even the first two episodes of series 6 led, Smith would be much higher in my lists. Usually, a doctors first series is my least favourite (this goes especially for Tennant who I didn't like until late series 2, took me a while to place him above Eccleston. Not so keen on Pertwee's first either, prefer his later stuff). I think I preferred series 5 to series 2 (apart from a few series 2 episodes like Rise of the Cybermen/Age of Steel, Girl in the Fireplace, and Army of Ghosts/Doomsday), so if series 6 and 7 got better like they did for series 3 and 4 with Tennant, Smith could possibly even be in the higher end of my doctor list. Alas, they gave us the shittiest series of new who or possibly even entire doctor who which was series 6 with a tiny amount of decent episodes, then series 7 which was rushed to a stupid level (when I say that, I mean the episodes were rushed with silly last minute endings and the doctor using his sonic screwdriver all the time to get out of bad situations)