I have only used the clubs a few times so far -- three times at a driving range and once for 18 holes. The big difference I found between these clubs and my old set (Wilsons) was how solid they feel when I strike the ball. The feel gives me more confidence (which may not be a good thing at all times) and allows me to be a little more aggressive. Case in point, on one hole during my last round, I was faced with 195 yards to the green, with the last 30 yards over water. With my old clubs, I would have laid up to the water and chipped on. These clubs felt so good, that I decided to use my 3-iron, and put my shot on the green, 10-feet from the cup.
I haven't found anything I don't like about the clubs yet, although it did take a little getting used to the 3I, 4I and 5I with the wider sole.
I spent a lot of time on sites like this one, researching irons before making my purchase. I have no regrets whatsoever for going with the Callaway Big Bertha 2008s.