Fitment is great. I am 5'7" @170lbs with a 32" waist. I ordered a 52 based on me wearing armored shorts.
The perforation in this suit is amazing, I am a coach with STT. So coming in from an Advanced session right into a Novice session, then to the classroom without much of a break can be brutal on hot days. Do not discount the ventilation this suit provides!
The fitment in the legs and arms is almost perfect. I do however have to run the bottom leg zipper only about 60-75% zipped to fit over the inner AlpineStars SuperTech R boot system. This may not be the case for other boots. I would also say I have slightly above average calf size for my height/weight.
The arms fitment is fantastic, the pre-bend added to the elbow area is actually really nice, and seems to help with getting into and out of the suit.
The zip in liner is also a really nice treat. On my old Missile suit, my arms would get caught in the liner when putting it on or getting out of it. This would pull the liner off the Velcro, and get it all twisted. Super annoying. That's not the case with this suit.
The leather itself on this suit is soft and supple. I'm not a leather expert, but I feel like I can tell the areas where kangaroo leather is being used and where the bovine leather is being used. The tougher bovine leather is in the high impact, friction areas, and the 'roo leather is where you need the mobility/protection.
All in all, this is a tighter fitting suit than the Missile (only other suit I've owned) However, due to the stretch sections, and accordion panels I believe its fits BETTER and SAFER than the Missile. This suit seems to contour my body much better, this allows all of the armor inside of the suit to stay where it needs to be while your riding, and that's as close to the anatomy they are designed to protect.
My one and only gripe with this suit is that when putting it on I always seem to get one of the lower back/butt armor plates flipped inside of its pocket.. This is more of a slight annoyance than anything, but that's the ONLY issue I have had so far. It also takes about 10-15 seconds to reach back there and flip it back..
All in all, this suit is well worth the money. It fits tighter than my old Missile suit, yet I feel like I can move more freely in it. I absolutely recommend the AlpineStars GP Tech V3.