My sister has one.  They are very cute and fuzzy but keep in mind that MOST toy dogs are very difficult to housebreak.  They also tend to have teeth problems from such small mouths.  They are great lapdogs but not generally great for small children since they can get hurt easily and can get nippy with kids (like any toy dog since they get nervous)
Training shouldn't be terribly difficult since they are pretty food motivated.  They can get fat very fast though, which will cause health issues down the road.