I've only had experience with the Mod.2 subcompact I own, but I don't think anything changed mechanically between the two models. I believe the differences were entirely in the grip (I could be mistaken, but they're at least similar).
Some describe the gun as "overbuilt" as it's fairly heavy--heavier than a Glock or M&P of comparable size. But it also feels well made. I've run about 3000 rounds through mine in the first year and have never had a jam or failure to feed. It's been rock solid reliable, and its size fills a perfect niche for me. The grip is short enough to conceal well, but still holds 13 rounds, and the overall length is quite compact so it's easy to carry AIWB without digging into my leg.
The only thing I've experienced, and recently, is extended magazines coming unseated while firing--it's a little unnerving. It's never happened on the flush fitting 13 round mag. Someone suggested using the extended mags without the grip extension sleeves, and I'll try that. I know I've rammed those suckers home when the sleeve isn't present. If I continue to experience that intermittent issue, I may need to get it back to Springfield for a checkup. I've confirmed that it's seated (I always tug the mag to make sure) and that I"m not bumping into the mag release button.