Old thread but I'll chime in because I generally love this style - unless it's a split foyer.
Multi-level houses are often Mid Century Modern in style. One of the biggest mistakes I see is that homes like this have been ultra modernized which kills the origional character and leaves the home with an identity crisis of sorts. This is a style of home that looks best when it stays in the MCM vein.
The only downside in my opinion is that sometimes bi-level homes run short on basement space. If they're done "right", there are two basement levels which allows for a family room space and then storage a half-story down. If it's missing that lowest level basement, it can feel really small.