Saw this yesterday. I was kinda expecting to be blown away by it, but instead I found it pretty good on some aspects, and kinda dissapointing on others.
SPOILERS AHEAD
What I liked about it:
the whole gameshow angle was quite entertaining, mostly thanks to the great performance and presence of the guy who plays the gameshow host (loved the way he says "Who wants to be a MILONAIRE"

)
The visuals and locations were very engaging. Just the sheer scope of the slums and the grittiness of it was portrayed very well (of course you would expect this of Danny Boyle).
The soundtrack was very good and fitting (again, no surprise from Danny Boyle).
I enjoyed the first part of the movie a lot more than the second half, where it seemed to turn into this quite unbelievable and formulaic love story. I mean the central focus of the whole plot was this love between Jamal and Latika but at no point is it ever shown or told why they should be together. Apart from the fact that they spent some time together as kids in the slums and then got seperated, I don't think they had any really developed scenes where you could sense that they loved eachother (or would love eachother in the future) or that they were the soulmates that were "destined" to be together.
It just didn't seem believable to me at all and made me not really care for the characters in the later parts of the film. The characters also seemed really 2 dimensional. We have Jamal, the kinda introverted hero who's only purpose in life seems to be chasing after this girl for no apparent reason (or at least nothing that's really explained).
The girl on the other hand never is shown to take any real initiative to find Jamal, and has to be literally pushed out the door to actually try and find him in the end. Then we have the brother who for most of the film seems to just be a criminal dickhead and suddenly at the end turns around to help his brother and lost love get together (very conveniently).
Anyway, this all didn't detract so much from the movie that it became unlikeable, but it was kinda dissapointing in that respect. But the structure of the movie with all the vignettes of Jamals past as relating to the questions on the show was fun and interesting enough to counter some of the cheesyness later on.