Shih tzus are great for small homes. They are very active and playful while you are there, but total couch potatoes when you go away. Mine do bark when they see people outside. This could be a problem for some people. I solved that by keeping the mini blinds so it lets in light but they don't see outside too much. In the summer they bark at the very noisy neigbor kids--but these kids are so loud I want to fuss at them too!
Even if you can't get your dog yet, spend time deciding what is the right one for you. When the right one comes along, you will know it if you have done your research.