Pros: Surprisingly Forgiving, Clean Look, Smaller Head, Fitting Process, Not Painful to Mishit
Cons: Sole Scratches Quickly, Shaft Upcharges Apply, Shipping Time, Stock Grips
After going in and testing various irons, I decided to purchase the S55 irons with KBS Tour X-stiff shafts in them as the Mizuno shaft fitter recommended. This is where two of the three cons apply. It was a $10 a shaft upcharge to go to the KBS Tour shafts (which is fairly reasonable, but still worse than free) and I was told that they would be shipped directly to me due to the store not carrying anything above a stiff in stock. They gave me an estimated wait time of one week, which seemed reasonable enough. Unfortunately, contacting PING directly let me know that it would be a week before my order was even processed and shipped. This isn't really PING's fault though, more of an issue with the salesman trying to sell the clubs. It ended up taking around two and a half weeks for the clubs to arrive at my house, but it was worth the wait.
When I first took the clubs to the range I wasn't quite sure what to expect in terms of trying to not take massive divots. The combination of brand new clubs (a new experience for me) and a thinner sole led to me thinning most of my first shots just because I didn't want to take large divots or scratch the sole. The sole ended up scratched immediately though and, after a couple trips to the range, I was able to overcome my fear of taking beaver pelts enough to realize that these clubs actually take smaller divots than my old Ping Eye 2's. While they still take a satisfying chunk of turf, it is still a reasonable size that's smaller than the touted "dollar bill" divots. Even on low punch shots I don't have to worry about digging trenches.
As to the forgiveness of the club, I was pleasantly surprised in this regard. I found the clubs to me not much less forgiving than the i25 irons, and the only time there was a noticeable difference between the two was when you hit it far out on the toe or if you hit it fat. Thin shots or slight mishits had the same trajectory from both irons with the S55 traveling further on equally well struck shots. I did also find though that the S55 traveled further on purely struck shots than the other clubs I tested (excluding the Taylormade MC irons), which was a nice plus considering they also had the tightest dispersion of the bunch.
On the course these clubs proved themselves to perform well from even what would qualify as less than favorable lies. In one day where I played 27 holes of tournament golf I hooked 8 tee shots into ~12" native grasses. Each time I was able to at least get the ball out and advance it somewhat, so the clubs can cut through the rough just fine. They also remained just as forgiving under the stresses of tournament play as they appeared to be on the range, which is nice since I know sometimes a club will feel fine until you get into a pressure situation.
The aesthetics of this club, to me, are phenomenal. From the top it's near impossible to tell you aren't hitting a straight-up blade (which, to me, looks very pretty) and the back of the club doesn't give away much in terms of how easy to hit a club this is. Switching to a small silver emblem in the club's cavity was a nice change to me from the S56 iron, and it helps define the club as "sleek" to me. I also like how the clubhead has a matte finish to prevent it from blinding you at address like some other clubs do *cough cough* Mizunos *cough cough*. Overall I'd say it's the prettiest club that PING's ever made.
The feel of the clubs is nice, but it's different than I expected. To be honest, you don't feel a whole lot going on in the clubhead when you hit it solid. The sound of the club is a bit clickier than most forged offerings but, unlike the aforementioned forged clubs, it doesn't hurt at all to mishit. You can feel if you hit it thin or thick, off the toe or off the heel, but it isn't painful. I know the MP-59's physically hurt when struck more than a smidgen thin and the Titleist CB irons were much the same. PING engineers did a good job with the Custom Tuning Port (just barely visible tucked inside the sole of the club) in that it dampens painful vibrations but with a - in my opinion - small tradeoff of the feeling of hitting nothing on the solid shots. I kind of like it that way, as it lets you know whether or not you hit it precisely in the sweet spot by whether or not you really felt anything in your hands or if you just heard it.
The main reasons I took off half of a star in the overall rating (and a small amount in the value column) are the sole scratching and the stock grips. The sole scratching just means the bottom of the club doesn't look as beautiful as an off the rack club for long, which is fine but I expected it to last more than a couple hits with a cast club. The stock grips are my only real disappointment with this club. I like how Mizuno offers 31 different stock grips when you get custom fitted for your clubs (including the Golf Pride Multicompound grips that I like), but PING only offers two grips: a rubber and cord version of their stock design. I ended up purchasing the clubs in-store with stock shafts and pulled my old shafts with near-new grips to put on these irons just because it gave me the shafts and grips I wanted at a cheaper price than ordering them through the store that way.