Liquid Planet is definitely all right. I've had a few of the pita-sandwiches, and they are all pretty good. Some of them are really delicious, like the Tricia's Delight (cream cheese, sliced apples, raisins, walnuts and honey). Others are a little underwhelming, like the Veg-Out, which was really just a bunch of veggies in a pita.
This is a weird complaint, but their pitas are overly crisp. In an attempt to serve up a warm sandwich, they torch the life out of those poor things. And also, if you get a side of hummus, they serve it with tortilla chips. What?!
Yes the smoothies are really good, all of them. I'd recommend trying something a little off the beaten path.
It's also a cool place to spread out and study with plenty of natural light.
So what is the cause of the three stars? Prices. The smoothies and sandwiches are just too damn high for what you get and the quality of it. Overall, try it, it's good!