Lean Cuisine has to be the best tasting frozen meals I've found. I've been doing the Simple Diet by Dr. Anderson (there's a forum on it over in the General Diet Plans and Questions section of the board) which is similar to the NutriSystem diet I think. It's basically a meal replacement plan that uses shakes and frozen entrées. It's also not expensive at all. I think I spent $58 at Walmart for about a five day supply.
As mentioned above, a lot of people are concerned about the sodium content. I'm not entirely sure how much sodium you're supposed to have, but according to the one day that I logged everything on the My Fitness Pal app, it says I had less than 2000 and that the daily recommended was 2500. So yes, it might be greater than it could be, but the diet itself helps with portion control as well as convenience if you're on the go and/or don't have time to cook.
I will warn that on the Lean Cuisine front, you can't use all of the meals on this diet as they have to have less than 300 calories 9g of fat and several of the meals are over 300 calories (though not by much).