Had the opportunity to play last night - though not for long as there was a double episode of Heroes on.
First impressions are that it is good. Played through part of the first campaign and then a bit of on-line action (finished last with the least number of kills - which is not surprising as I haven't played Halo in ages)
The Beta of COD4:MW ends on Sunday at 12:00am PST.
So looking forward to tonight and some more fun - hopefully I get some better scores.