…and loved it!
I finally got around to ordering Arkham Horror after getting that itch for a new boardgame which I'm sure everyone here is more than familiar with 
I've got a good sized gaming group that I regularly play with but I bought this with the original of intention of largely playing it with the four most tightly-knitted people as we see each other all the time. We don't really have any fully co-op games (i guess the closest would be battlestar galactica) and Arkham Horror seemed quite unlike anything else we own. My girlfriend and I decided to try it out over the weekend to learn the rules before we try introducing it to other players and we were pleasantly surprised to find that it works extremely well as a two player game (especially if you each play two investigators). We have quite a few other games in our collection but none are really satisfying when played with 2 players, Arkham on the other hand really was!
In total we played 3 games, two games with an investigator each and the last one where we each controlled two investigators (also the game we won despite the AO being Cthullu because we didn't get repeatedly screwed by those dreaded rumors!).
After our three games we were left with the following impressions:
This is a great game, it's truly immersive and we can't wait to play it some more and try out the expansions! Perhaps our favourite 'feature' of the game was that it's effectively a light-rpg. You get a lot of the story and immersion with barely any effort at all when compared with a proper RPG.
The main sources of criticism towards Arkham Horror are that it's 'fiddly' and the rules are unclear. Whilst I agree that the rules are unclear, they're not that complicated. The main problem is the rulebook could be layed out a lot better, but its a minor issue thanks to all the help out there on the 'net. As for the fiddliness I don't get it; sure there are a fair few counters which could be replaced by sliders but in all honesty I don't really see it as a problem. In fact, I like all the stuff you get in the box as it feels like i've got my money's worth. Besides, I play Twilight Imperium (currently my all time favourite) on a regular basis which IMHO is far more fiddly.
I've seen reviews of the internet that compare this with Fury of Dracula. This was the main thing that put me off getting Arkham for so long as I really, really don't like FoD! The only similarity I can see between them is that they're both boardgames. They're completely different in every other respect.
Play time is just about right for our purposes. We love our epic Twilight Imperium marathons but to be honest, its nice to have a game which you can play in an evening without much planning. Set up and pack-away time is quick (compared with some other games we play) and you get a good 3 hours or so out of it.
I'm really looking forward to introducing this to more people and spreading the word!
Cheers,
El