I have an interesting find- My friend sold me his figure which was in an unfortunate condition where the PERS broke, one eye was literally sunken too deep in the eye socket, one of the boot connector cracked, a missing arm fin, broken batarang and the cape has deteriorated that it was shedding crumbs and felt light. He said he never played with it but it had broken down due to being in storage too long.
Since I'm very familiar with this figure (it was my first HT and I've handled several of them over the years) I've concluded that there are 3 common issues to look out for with this figure if you're planning to get one or if you're just inspecting yours after awhile:
1) Cape. The quickest part of the figure to break down. The suit is thick enough that vinyl cream applied once a year is more than enough to keep it in pristine condition, but the cape is made of pleather that will eventually become sticky due to deterioration. You can also use some vinyl care products on the cape.
2) The PERS, which most likely will break in time but it's not the end of the world. All you need to do it to unscrew the cover at the back of the head and disconnect one of the tabs so that the plastic doesn't link both eyes anymore. You'll loose the PERS feature but you'll now be able to manipulate each eyeball individually.
3) Boot socket. This is almost inevitable just like the Batman Begins figure. The boot socket cracks easily and I've seen this on more than 3 figures now. I'm planing to use epoxy on mine and just lock the boots to the feet peg.
I also saw a video on Youtube about applying products to the figure, however DO NOT apply any on the cowl, boots or arm guards/gloves simply due to how easily the plastic shines and make the figure look like *** because the actual cowl in the film was matte. Having a shiny cowl is just screen inaccurate.