I've been playing Ping i25 irons since early in the 2014 season. I was fitted for the clubs outdoors and the clubs were custom ordered to my specs. I've been quite pleased with the results I've been getting from these clubs since I bought them.
When I ordered them I only purchased a part set, 6-PW, as I had a number of hybrids that I thought would work well in conjunction with these irons. My fitting specs are 1.5° upright lie angle. I've found that the hybrids I had were too flat to blend in nicely with my irons and that led to acquiring a different hybrid last summer to bridge the gap between the irons and the fairway woods. That has proven to be a less than ideal solution.
With the above in mind I decided to order the matching 4 and 5 iron from Ping from their back catelogue to fill out my set of irons to matching spec and serial number. Ping provides this service to existing customers at no additional cost. Despite the i25 being out of production for over a year, the per unit cost was the same from the back catelogue as I paid when I ordered my original set. It is actually cheaper than what Ping is charging for the replacement iE1 currently.
The irons arrived today at the course pro shop that I ordered them from to take advantage of a shop credit I had for clubs I had consigned to their annual club swap earlier in the month. It was rainy, cold and very windy today so I didn't get much of a chance to audition them, but I did take a few cursory swings and hit a few balls. I've got the confidence that I can hit the long irons based on my experiences with vintage clubs. Ballflight is quite strong versus what you would expect from a hybrid, but I felt like I was still getting pretty good carry even from the 4 iron. There is definitely going to be more run-out than with a hybrid, but the tendency to go left is solved with the irons. Looking forward to getting these out on the course for a more thorough introduction.