Call of duty: world at war is the best FPS on the wii to date. It beats medal of honor in every single way...
1P. The first player experience is pretty short. So if you do not have online i would suggest dont buy it or just give it a rent. The campaign is still better than MoH. there are a lot of great videos and the flame thrower is very fun :)
Controls. This one i would have to give to MoH: H2. But CoD controls are still very good. it might take awhile to get used to, but eventually they become very easy and natural.
Online. This is the sole reason that CoD is way better than MoH.
Yes MoH could have more people per match, but who really cares about that. In CoD you can customize your own weapons, chose your perks, level up, and prestige.
This is what makes the online addicting. You just have to keep playing to become a higher level, and to unlock cooler weapons and perks.
The downsides to CoD: WaW on the wii are that the matches can only be 4 Vs. 4. Some levels are really big and you cannot find other people when there are so few of them. Hopefully they get it right for the next one.
another downside is that there is no offline multiplayer. The only thing you can do with a friend is play co-op (which sucks by the way).
The last thing that is disappointing is that wii version was left out on some great features. For example Nazi Zombies and some other online modes.
If you own another system i would recommend you to get CoD: WaW on that, but if you only have a wii and you love FPS' then this is a game for you.