I just got mine yesterday and slapped the armor on my Roy -1S.
I have a few gripes and a few praises. Sorry if people have already mentioned these.
Gripes:
-The weight. The added weight of the armor with your valk makes it a pretty hefty toy. Normally, I wouldn't complain (and I'm not really complaining right now, just saying) but I'm afraid of the amount of stress this is putting on the valk's ankle joints. I don't want to end up with a valk that can barely stand up, like my old 1/60 Hikkie -1A.
-The chest missile compartment. The bad thing about this is that if you take the compartment apart, you'll see that the doors are connected to the missile storage by a very tiny piece of plastic. So, if you're having trouble loading the missiles, and push a little too hard, the plastic will snap and your missle locker will no longer "pop" out when you open the door.
-Loose wrists. The arm armor's thickness prevents the hands from properly gripping and posing the gunpod. But, the main problem here is that the wrist joints in the new hands are really loose so you end up with a buff-looking valk with limp wrists.
The praises:
-The amount of detail is amazing. I love how every single missile is detachable and I really like how they paid attention to what's underneath the armor as well.
-The stickers. They're not great but they are a vast improvement over what Yamato has produced in the past.
-The production of the toy itself. I never thought I'd see a 1/48 GBP but now it's here and Yamato really did pay a lot of attention to this toy. The quality of the plastic, the look and the overall fit and finish are all really well done.
Sorry about the rant!