I made the switch from Ping i5's to the Burners back in April. I have +1/4" (I am 6'1" tall) stiff shaft, +1 degree upright specs. I usually shoot in the low 80's. So far, I have had mixed feelings:
Pros: The clubs are easy to use thanks to the progressive forgiveness. For this reason alone, I would suggest any mid-handicapper to use these if they still struggle hitting longer irons. I also hit the Burners about 5-10 yards further than my old clubs.
Cons: The irons are longer than other models and take some getting used to. It encourages a flatter swing plane. In addition, the clubhead is larger/heavier and takes more effor to swing down, especially if you have a large swing like I do (my backswing tends to go a little past parallel). A flatter swing and a heavier club head have caused me to hit thin shots, which was never a problem for me before. Another problem is the quality of the club - I have broke my 9 iron twice so far on standard shots from the fairway/tee box. The first time I broke the club I had to wait 3 weeks for Taylormade to fix it (for free since it is still under warranty). Now, less than a month after getting it back, I broke it again. I'm not saying that every set will be like this but I am questioning the quality of the clubs.
Overall, the ease of use should make this set appeal to most golfers, but it is not for everyone. If you already have a problem with flat swing planes or topping the ball, stay away. I will probably stick with this set although if I had to do it over again I would probably have waited for the Ping i15's to come out.