Matt Smith is a feeble copy of Tennant, and it's not really his fault.
All the producers have done is keep a Tennant style doctor in a younger man's body. But every action he makes is a knock off of the real thing.
When the Doctor's regenerated previously you always knew it was going to be different, this time round they've just made him younger.
If it ain't broke I suppose.
The boy could be a truly great doctor if they just changed him a bit, for example stop his use of intimidation he can't carry it off, that's not a criticism it's just a fact the same way Patrick Troughton or William Hartnell could never make someone as terrified as Jon Pertwee. That's not a sleight against them, it's just their Doctor's had different strengths.
Give him time. Every new Doctor starts off differently than they end up.
The last three have all been different than (most) of their predesessors - in that they have all started their new role in a borderline manic state. Once they feel their character out and the writers get a chance to tailor the scripts more closely to what the actor is and has to offer, they tend to settle down and offer something far more than their first series.
I think Smith is doing quite a good job - his intimidation, I think, is a byproduct of his mania and borderline psychosis - he's more trying to hold himself back than the people around him - he's also making rash decisions and promises - which is different than the other two - if something was potentially beyond their power then they'd never promise something they couldn't deliver - he is doing it all the time.
He's got potential - but so far no one has got near Tom Baker.
At the moment, in order of how good they wer ein the role, It's probably;
1. Tom Baker
2. Eccleston, Pertwee, Davidson, Hartnell, Troughton, Smith
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McGann
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McCoy
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Colin Baker
And an Honourable menton to Peter Cushing who was ace in the films.