I've been saying this for a while now but as much as I love the A321s, I hate the seats. Especially on flights longer than 2.5 hours. This goes for all seats, not just Mint. They hurt my back as well and I don't typically have back problems. I will not fly on an A321 without an EMS seat.
That said I had my very first Mint experience last Thursday. I probably made a mistake but I booked the window seat in the section of 2. If I ever fly Mint again, I will book the suite. Long story short, I boarded first. Within 2 minutes, a guy and wife board and he was immediately confrontational(no hello, no good morning) with me and asked if I'd move so they could sit together. They had 2 aisle seats right next to one another. I kindly declined and said I booked and preferred a window seat. It turned out the window next to him was unoccupied so she moved anyway. He ended up glaring at me for the entire flight and/or complaining loudly in another language. I did discuss it with the FA and even he said I did nothing wrong. I like to keep my windowshade up so he also complained to the FA about the light. So several times I had to put up the trays to block out the light. Meanwhile this guy never even bothered to put on his eye mask or sunglasses. he was just looking for any excuse to pick on me for 5 hours. So it wasn't a very positive Mint experience for me but had nothing to do with the service.
As for the amenity kit, there was one item alone inside that was worth at least $50. And I thought there were some cool items inside like eye gels. So I had no complaints. I enjoyed the food except I thought the french toast was iffy. I probably didn't explore the seat features enough but I did recline fully for a bit. I agree it would be nice if the seats reclined in a seated position too. I could barely feel the massage feature when I tried it. Overall, a good experience aside from the crowd.