All small dog breeds seem to be more prone to dental problems than larger breeds. My vet said that there is something different about their saliva that causes them to easily develop gingivitis so being a Pom is a small breed, I'd say that they would need their teeth cleaned often (either in the form of a tooth brush, raw bones, etc.). In my experience (a friend has three) they can be pretty yappy. Two of the three I know are yappy, but they do stop barking when told. They seem to learn new things relatively quickly too. Their coats do need consistent upkeep so as they don't become matted. A lot of small breeds are difficult to housebreak, including the Pomeranian (like Lute said). You just have to be consistent in taking them outside often and praise them like crazy when they go outside. One accident in the house will set you back a lot in training. I never, ever recommend puppy pads or newspapers as a form of training. In my opinion, all dogs should go outside (unless hawks and such are a big concern, then my opinion changes).