Zombies is absolutely brilliant, the smaller survival maps are just like the old days of WAW and TranZit is really good fun. I really like getting on the bus and moving around the map and having to fight off a massive zombie wave while on it It's also neat that you can build items & weapons out of random parts and that there are some new weapons. There is a lot of exploration to be had
After an evening playing with a couple of mates I would now agree with you. The floor catching fire is still really irksome, but I enjoy building parts and the zombie shields are an awesome idea.

I think I will play zombies for a few weeks until I am bored of the maps and then that's it for me, I will bash through the campaign for the achievements and just to see what the new "control a squad from above" mode is like then I will sack it off.
Sack off the MP, but combat training in custom games is great fun if you have a couple of mates to join in, especially now you can modify so many options. We play hard point on nuke town and the other smaller maps, choose four teams of three, (us three and three bot teams) and its a right laugh. You don't get any XP, but everything is unlocked straight away. The EVO SMG is an awesome weapon.