In reply to ActionSte:
hey man! so a while back i was in your situation more or less (a little experience perhaps). I can only talk about my experience, which is public sector tree works (parks and street trees in london. this can mean some truly massive trees) and estate woodland work.
firstly a warning: it really is very physical. and, though i'm only in my mid twenties and would consider myself fairly fit, it does knock lumps out of you and it will, without question, impact on any physical hobbies.
also, sometimes it actually is quite fast paced and fairly pressured. often there's a big drive to get more done, faster. the more work you do, the more money you make. This doesn't change when it starts raining.
finally there's also real alpha male problems in the industry. You will at times feel pressured to do more, or things you might not want to do. this leads to stupid decisions and pushing yourself harder than you may want to on any given day. if you feel confident you can rise above this, then it shouldn't worry you.
lastly, it is an industry where employers always get their pound of flesh. You'll get payed, you won't be broke, but there'll definitely times where you feel like you deserve more than you're making.
having said all that it is generally varied and satisfying, the more technical jobs like dismantling big trees over people's property are interesting and enjoyable challenge, and when you get up into truly special trees from time to time (i've been up some of london's biggest over the last few months) then those really are quite unique experiences.
for a employee there's lots and lots of work. if you're good, and make an effort then you'll stand head and shoulders above lots of other people. check a forum called arbtalk.
lastly, I've got to be blunt and say that as much as i enjoy this work i will, without question, get out of it before i'm old. before i'm even middle aged for that matter. it's certainly possible i end up doing something within the industry but off the tools, but i have to bear in mind the real possibility that 10 to 15 years from now i'll be retraining.
also i would echo the comment above about the inevitability of accidents.
good luck, it's fun! and stay safe