About disadvantages and advantages.. the disadvantages Modo would have compared to Cinema4D would be that it's not yet a fully featured application so you can't do everything in it yet, however this may change now with Modo 401. We'll see what more features this release will have when Luxology reveals them.
One advantage of Modo is that it has a much lower price than Cinema4D has, so it's easier on your wallet which is always a good thing. And they give you fast and good help on the forum if you need that. You can write your own script for anything in Modo and that helps when you work, it supports instances and sss and displacement and renders at impressive speeds. But personally i am not very pleased with the materialtree in Modo, this is something i hope they have improved and made more userfriendly.
Cinema4D is a rockstable solid application with tons of real nice features and stuff in it. As it sells as modules the cost will increase quite a bit depending on which extra modules you want for it. C4D has a huge usercommunity and it's a friendly helpful one. Plugins and external renderers exists in all flavours so you can pick whichever one you like to use. All of them are well integrated into C4D.
Modeling is definately easier in Modo, i can't say the same about Cinema4D's modeling tools. However they're still usable.
There's much more to say but my fingers can't take writing much more at the moment.

sorry
/ Max