I took a look at that map. Seriously? One of the reports said service inside my local Von's is bad. Duh! It's a metal building. Some others (using all three carriers, in fact) reported poor reception in their houses right near where I live. I have excellent service in my house using AT&T. I found one report at a freeway intersection (no houses) between a cut in the hills out by the coast. Gee, a dead zone in the middle of nowhere. Many of the reports in my area were from 2008, and I bet a lot of towers have been installed since then.
My point is that this map is extremely subjective. It certainly is not scientific. And no service, on any carrier, is ever going to be 100%. There will always be dead zones, but some are to be expected. When I go into a ride at Disneyland, deep in the bowels of the earth, gosh, no service. In a metal retail store, girders everywhere, the same. Should you be able to get service in your house? Yes, in most cases. That's why there is a cooling-off policy after you buy a phone, so you can return it if you get home and discover it won't work there. All carriers have stronger and weaker areas, and phones seem to have better or lesser antennas. But are we to expect strong cell service everywhere? Well, if we want to be disappointed I guess we can. Service is evolving, and carriers will always struggle to fulfill our "needs."