Construction is top-notch as you would expect from Mizuno.
I first picked up an 18* Fli-Hi to go in my set instead of a 5 wood. I had intended on picking up a Taylor Made Rescue, but after hitting this one I couldn't settle for one of those. It has the control of an iron, with no bulge or roll, the face is flat. It is very difficult not to hit this thing straight. The hollow iron head creates a lot of speed and spin. Hits are high and land flat. I replaced my 3 and 4 irons with the 21* and 24* recently and love the set.
I hate the standard grip. I have a very strong grip and they gave me blisters. I replaced them with Winn Tour Diamond, and now think they're the perfect long iron.
If you have trouble with your long irons you should definately consider dropping at least $200 and get the 21* and 24* to replace those hard to hit 3 and 4 irons. Drop another hundred if you want to get rid of your 5 wood or 2 iron. Actually my 18* Fli-Hi outhits my 15.5* 1 iron so if you have 1-PW set you could actually save a club. I also had to get a strong 3 wood to make a difference in the Fli-Hi's and 3 wood. Definately my favorite clubs.