Hi Calico
If you're used to Rhino and nurbsmodeling in general and you never really done any polymodeling before, have you ? if no then you will find it difficult to get into Modo and all that it means. It's gonna take you time to learn it, no doubt about that.
However if you do have previous experience from polymodeling then you will find it easy and quick to get into Modo and to learn it as it's very userfriendly and intuitive compared to many other modeling packages.
To be honest i wouldn't compare Rhino and Modo at all, they're very different, VERY! it's like night and day difference.

first of all one is nurbs (Rhino) and one is polygons ( Modo), that in itself is enough, but the workflow and the tools all differ alot from eachother. Booleans as a example are not as easy in Modo as they're in Rhino, often you will have to model holes in a model yourself to avoid the issues polygonal boolean tools give you, the same is true for Modo.
The bad things in Modo would be that it still suffers from bugs and that it will take time to learn everything and that polygonalmodeling is often a slower method to work with than nurbsmodeling. It's more complex and a hell of alot more mouseclicks and movements to do.

if all that doesn't bother you then by all means go ahead and use it.
The good things about Modo, well they're quite alot and i think they're shadowing over the negative parts enough for me to stick with Modo as one of my main programs. Such as once you learnt polymodeling and got up to speed with it then you can quickly model accurate good looking models and easily UV them and paint any textures you need for your model directly in Modo without having to run your model through several different apps just to do all that. It's all baked into one single application now.
But i have to recommend you wait for the demoversion and give it some time and try it for yourself to make your own opinion about it. That's what really matters, if you feel at home with it or not.
Btw, recently one guy on the Modo forum built these models for fun but they're a good example demonstrating the type of work i guess you would do with Modo. It's very well done with nice clean models.
http://forums.luxology.com/discussion/t ... x?id=19540
/ Max