Cellular Shades for Energy Efficiency

Since remodeling the living room, I've been looking for window coverings that will enhance the new colors and keep the room cool. The big window on the south side lets so much light in, and it gets so hot in the late afternoon, even with the room darkening mini-blinds closed. I'm just not happy with how much the air conditioner has to run in order to cool that room in the summertime.

I found these cellular shades online that are supposed to make your home more energy efficient because they absorb the hot/cold air coming in through the windows, as well as blocks the UV rays to keep the room either warmer or cooler, depending on the season. They are more expensive than anything I've ever bought in the past, so I'm a little hesitant to buy them if they aren't going to be any different than the mini-blinds I already have.

Do any of you have any experience with cellular/honeycomb shades? Do they really make a difference in helping to keep the temperatures comfortable inside while lowering your electric bill? I really like the way they look, and if they perform the way they say, I'm planning to buy them. Let me know what your opinions are, please!