Very good for both the Razr and Razr Maxx, at least compared to older phones.
My home is in a low-signal area, and reception inside the home has always been spotty with many different brands of phones over the last few years. I bought a Droid Razr on Jan 15th (last day for the 4G/month data plan promotion), then exchanged it yesterday (Jan 26) for the Razr Maxx. Both of these phones are much better than our old LG flip phones, so much so that we can make and receive calls almost anywhere in the house now. Big improvement from the old phones.
Can't address the issue of 3G and 4G data reception, but this seems to be good when traveling away from home. We don't use the phone data when home, relying on WiFi instead.
The Razr and Razr Maxx seem to be slightly better than my wife's iPhone 4s inside the home, but it's hard to discern the difference by actual phone calls. This observation is based on the number of bars displayed, but I consider that questionable. The mapping of bars displayed to actual signal strength is somewhat arbitrary and varies among manufacturers. Bottom line is that the Razr, Razr Maxx and iPhone 4s are much better in terms of cell phone reception, compared to older phones.