Dude, I'm in the exact same boat here. I love Arkham Horror, it's quite another beast to Zombicide, and I will get some expansions for AH once I've paid the Zombicide season 2 kickstarter.
What I love about Zombicide is that it's fast and fluid, one second you're doing really good, next second massive zombie spawn and they get an extra activation and you're surrounded by living dead. It does have some holes in the rules, but they are easily house-ruled away. Everyone in my group loved it even though we ran scenario 1 for about 6 hours (one of the hardest in the book). We have session 2 on Friday, so it will be a shorter scenario, most probably from the campaign GG have put up on their website.
Personally I think it is well worth the money. But my group is a new group in that they haven't really played many board games, so perhaps "veterans" would feel differently. Please let me know what you think once you've had a chance to play it.