I started skydiving about three years ago. At first I bought open face helmet since it was cheaper, but quite soon I also bought Kiss. I do not have experience of other full-face helmets.
Kiss fits my head very well. I like the design, it's light and I like the exposed audible pockets. After wearing Kiss for a while, though, I learned few down sides.
The vizor mechanism is not very good or strong. First time wearing the helmet the vizor was not locked properly and it was torn of by wind while I was spotting. Later I learned that this is known feature with Kiss. Nowadays when I go to wind tunnel the instructors always test my vizor mechanism. I've learned to live this one, though, and it has always stayed closed during freefall. Sometimes I also accidentally close the vizor during landing (especially swooping). It is not very pleasant surprise.
It is quite hard to mount a camera to Kiss. I guess it is hard with all full-face helmets, but I think that the shape of the helmet and the vizor makes it more difficult compared to Cookie G*, for example. Chin mounts work, but those have their own issues.
Finally, if you want to protect your head you could as well wear a plastic bucket. I suffered quite a bad injury recently, and God I was happy to wear my Cookie M3 instead of Kiss. I hit my head hard and I think that the extra layer of impact-absorbing material saved from a real brain injury.
So, if I had to buy a new helmet, being more experienced (still not really experienced) skydiver I would by Kiss. I think I'm going to by some helmet to replace the M3 that took a hit, but Kiss can stay in tunnel use.