I got back into golfing about 2 years ago (and some change) after a very, very long layoff (10+ years). I came back to with no semblance of a game except putting that wasn't a complete disaster. My biggest problem has always been ball placement for the different irons. Also, because coming back after that long of a layoff (and I was never really a regular player 10+ years ago either) I'm basically a beginner.
Being that this is my current state, I figured "why not" and put together a set of the DTG single length irons to try to become a moderately consistent iron striker. And, I can say this with complete honesty, it has made a world of difference.
Shorter irons were never THAT bad, but anything over a 7 iron was basically a no-go. Hit a 5 iron clean? Get the !#$* out of here. Now, with the single length irons, I can hit a 5, 6, and 7 iron. I almost crapped my pants the first time I hit the 5 on the course. Not having to mess with ball placement or different swing for each iron has made life for this Ogre much easier.
With these single length irons, I went from being an atrocious iron player, to an almost not that terrible iron player. So, I'm a fan of them. But I definitely don't think that they will make any great difference for someone who has been playing the game for a long time.