My mom has bunches of them and loves them. I personally don't get the hype. My moms have all cracked over the years, and while they do offer a lifetime guarantee (which is great), my mom never seems to take the time to mail them in. Plus, while it's true they don't sweat, I don't find that they do a good job of keeping things hot or cold.
The drinking product I'm nuts about is the Hydroflask. They recommended it on the DIS Unplugged podcast, and boy were they right! It keeps things ICE cold for 24 hours and doesn't sweat either. Of course it's not a glass, but it's a great product.