Chihuahuas are a great breed.
Overall healthy breed with not as many health problems as other breeds, they are a long lived breed. Do your homework, do not purchase from a back yard breeder, as they DO breed unhealthy and unstable dogs with problems since their only criteria for breeding is size. There is a lot more to producing a good Chi than size alone. There are a lot of sterotypes surrounding Chihuahuas, also just as many surrounding cats!
You have to know better and live with one of those devoted dogs to really understand them.
Their size does require special considerations (they can be up to 6 lbs. but some also reach more than standard, I have one that is over 6 lbs.) and also when they are puppies (like most puppies) they need very frequent feedings due to their size. Many like to be warm, sweaters and heated beds are appreciated. I like to be warm too so it isn't a problem