Frozen Diet meals are loaded with so much sodium. The only convenience is the portion size which will tend to make you more hungry. The sodium will also cause you to retain water and you will not show a weight loss and in most cases - you gain. Then, you start to blame yourself and at this point most people give up and quit. It just isn't worth it.
How about making your own "frozen meals". I grill a bunch of chicken, turkey or salmon on the weekend, steam brocholi or stir-fry some veggies and pre-pack my own meals. That way I won't get bored and I control the salt. You do save $$$ in the long run. I keep a lot of salad and cut-up veggies on hand.
It's an investment of about 3 hours on saturday night to have food available during the week. Sometimes, I have so much food cooked, there is no excuse for not having anything to eat or no time to cook. I simply re-heat something I've already prepared. I can go almost 2 weeks without having to cook again.
Give it a try. I'd really stay away from frozen "diet" meals (Weight Watchers, Lean Cuisine, etc.) and make your own.