i quite like Ansari, i just think he is very inexperienced and needs time. I thought he definitely bowled too slowly for that wicket and test cricket in general, but like i said he is still young.... Mo has said a number of times it took him quite a while to actually work out the pace to bowl for test cricket etc...
I also think it was telling that Cook gave him the ball 1st on a couple of occasions before the other spinners so he obviously trusts him.
He gives the spin attack a lot of balance and the Indians are packed with RHB - even more so when Rahul probably replaces Gambhir (next or 3rd test).
As for Saqlain, Mo and Rashid both said in interviews he hasn't worked on anything technical it has been about mind set, being relaxed, what fields to set and when to set them, and most importantly enjoying bowling spin in India.
Which i see as the biggest difference in Rashid he looks so much more relaxed and therefore is able to get through his action more.