What essentially happens is that the light from the laser is absorbed by the hair under the skin, which then fries the hair at the root. What it doesn't do, though, is actually physically remove the hair. It's still exactly where it was, it's just that it's now dead.
After a treatment, the only noticeable physical effect is a slight swelling and reddening. There's no obvious reduction in hair. Indeed, for all intents and purposes it seems as if the hairs carry on growing after they're dead. They don't, of course. What actually happens is that they're slowly ejected from the skin, at a rate similar to their growth rate. So, you go on dealing with the hairs as you would do normally, until a couple of weeks later, it falls out. This is quite interesting in and of itself; it's odd to reach up and scratch your face, and come away with a couple of millimetres of dead hair lodged under your fingernail.
I knew all of this beforehand, so it was all somewhat expected, even if it was cool to actually observe it in practice. What I wasn't ready for, though, was just how effective the process is. The way I'd always heard it described was that each treatment would effectively give a thinning out of the hair, until eventually it was (all but) gone away completely. What I found, though, was that it worked more in clumps. I have patches of my face that have pretty much no hair at all, and (smaller) patches which are pretty much as they were before.
Now, I'm sure that with time, hair will grow back in the hairless areas, due to the way that hair growth cycles work, but even so, I have to say that even after one session, that's a fairly evocative example of how effective the treatment can be in the long term.
The other thing that surprised me was just how many blonde/white hairs I have, especially on my top lip. Due to the way that the technology works, darker hairs are much more easily removed than lighter ones, so once you get rid of the dark hairs, it's easier to see how many light hairs are left. I have a suspicion that the laser might not be able to do much to them and I may end up looking for electrolysis (which is agnostic about hair colour) to get rid of them. I'll cross that bridge when I get to it though, I think.
I'm also thinking about branching out to hair removal in places other than my face. Next priority would be my breasts, I think. I don't have a whole lot of hair there, but it's enough, and hairy boobs are so not attractive.
I can actually see it becoming somewhat addictive, though, in the same way that some people seem to get addicted to tattoos or piercings. I mean, there are plenty of areas of my body which have hair that I'd dearly like to get rid of, and where would I stop? I find the hair on my hands particularly obnoxious, for instance, but if I was getting that removed, then why not the arm? And then why not the underarm? Then maybe the bikini line? Then onwards to the rest of the body. Of course, getting the entire of my body done would cost an arm and a leg (for comparison, the cost for six sessions for my face was £440) and I'm hardly made of money, but still. It's not without appeal.
I also wonder how cost-effective it would turn out to be in the long term. The amount of time and money spent on hair removal throughout a lifetime probably gets quite frightening. I should do some maths to estimate how much time and money I might expect to spend in a lifetime and see if it's worth it. Though I doubt I'd actually pay any attention to the figures I ended up with, and would just end up doing what I wanted to, anyway.