I bought a tomtom a week ago and have used it almost every day to get used to it in a couple of different vehicles. It very rarely drops the signal and even then for only a few seconds. One place it drops is parking right in front of my house...which makes sense. I love it.
If I were shopping for a GPS, I believe I would eliminate this brand from consideration simply because their commercials are way big on the annoying scale. They give their product an silly name and then design a whole advertising campaign around that fact.