I was on HA51 and 50 in the past 2 weeks. Plane had lie back 1st. We sat in 11H and J. There is a bulkhead in front between 1st and the mini cabin in all of row 11. I am 5'6", DH 5'11". We had good legroom, but even I could not stretch out fully, maybe another 2 inches would have worked for me. I was not able to use an inflatable foot rest I bought for the flight. However, there was still ample leg room. I could easily cross my legs. I took one of my carryons out and kept it on the floor until we had to land. I just pushed it back against my seat and my legs went over it. I was also able to keep my purse down between my seat and the plane wall. 11 C and G stick out into the aisle a little so they had to watch out for attendants with carts. DH in 11H was able to stretch feet out into aisle.There are oxygen tanks behind seats 11 A, B, H, and J but they did not interfere with the seat recline. Most of the seats on HA51 in the mini cabin had problems reclining. They did not go back by themselves and it took my husband and an attendant to both push on the seat back to get it to go back. I saw the attendant helping others recline their seats. I read a review on SeatGuru that the seats do not recline. They do, just not very easily. No problem on HA50. Row 12 seemed to have more legroom as they could stretch out under the seats in front of them, but it is also 4 to the row and closer to lav and galley and no windows. I think I prefer my little 2 seat area with a tad less legroom to sitting in the middle.
I will add that the mini cabin was quieter and darker compared with the main cabin and 1st with only 6 windows and bulkheads in front and behind.