Hmm,, a short sweet answer or a detailed analysis.
First things first, whilst truly asking for opinions and perhap banter on given subject Azza, this is a definite Knee-jerk reaction to what is simply one bad race for Hamilton, usually (going on 2010-11) he'll finish 2nd 2nd 3rd 7th 1st 6th, and whilst still second in the standings we're already making up our minds that he cannot handle racing. Of course he can.
In terms of Hamilton over-rated, you can ask any forumner, the more common posters the better that if i feel Hamilton does wrong ill say it, im not one of the fanboy group. But. He is the best thing ive ever seen happen to Formula One. Himself and Alonso are a level up from a yet to TRULY prove himself Vettel, and then theres Jenson and the potential wdc's. There is nobody that can truly say they are a go for the win (senna) driver like Hamilton. He is the only driver since Senna deserving of that helmet. And hes the only driver capable of pulling off the stuff, he so regularly does.
- Outbraking Kimi whos 20 metres in front in Monza
- Overtaking Massa in Monaco tunnel.
- Overtaking of all people Schumacher in Monaco
- Winning a wet British Grand Prix from 4th place by over a minute
- Overtaking 32 cars in the first 4 races of the 2010 season.
- After coming under pressure from Kubica in 5th comes out first corner on debut race having passed Alonso.
- Finished on podium first 9 races of career.
- Finished ahead on standings in first season, then teammate reigning and double world champion Alonso.
And then you look at the rare times heis being overtaken, like when Massa tried it in Malaysia 2007, and like a seasoned veteran he lulls him into a move that has Masas outbrake himself. Hes just such a talented driver. Also, drivers never get any worse, we can see when the cars allowing, as it has been for most of Hamiltons career even 10/11 he performs with it. Even in Formula Renault he started last one race and first the second race, from 11th. Natural born racer.
Sometimes we see Alonso pull likewise moves, but it is, and it is very rare, even schumi doing it. But Hamilton does it at will. Perhaps Alonso chooses not to but hey thats the difference between them.
Onto your second question, its a very hard task in the F1 world to decide such, we know Man U will win more titles, same with Barcelona, but we can never say an F1 driver will, cause we cant guarantee their car no matter what team will be up for it. I want to give you some examples of multiple world champions careers, look at the spacings between their titles:
Lauda: 1977(2nd) 1984(3rd) , thats a 7 year gap between titles.
Prost: 1986 (2nd) 1989 (3rd) thats a 3 year gap, and then 1989- 1993 (4th) thats a 4 year gap.
Schumacher: 1995 (2nd) 2000(3rd) thats a 5 year gap for a driver racing with Ferrari from 1996, to his next world title.
It is completely normal and the way Formula One works that drivers dont just win titles on the trot. Its beautifully worked out to keep competition and excitement ( other then2000-05 but thats an anomaly), Hamiltons last championship was 2008 thats..... not even 3 years ago yet. Im personally of the belief if Hamilton has a top car, maybe even a top three car, but all the top three are evenly paces. He will risnse the floor with anyone else bar Alonso, who will push him to the end. If we look back at even 2007, when do drivers ever suffer from neutral changes like that in the last race with such a huge lead, when do drivers tell their teams they can see the canvas on their tyre and they still dont bring them in. Other factors lost Hamilton 2007, 2008? when do third placeddrivers fighting for the championship get promoted to first when the winner gets a disgusting penalty like spa 2008. Alot has been out of his control before, and still he won.
One thing does have a constant poke in my back and that is the curse of the British racing driver, 90 percent of all our champions, of which there are about 10 have only one world title. However this is mere superstition and ive always felt and said the best drivers always end up with the titles to compliment how good they were, some more then others but roughly its always the case. If Hamilton stays at Mclaren his whole career i have no doubt he will win at least a couple more titles. If he moves to Ferrari then its the same, and if Red Bull are here to stay, which i dont believe they will, then if he goes there he'll win every year

Alain Prost - Lewis Hamilton - Kamui Kobayashi - Fernando Alonso - Kimi Raikkonnen - Jenson Button