I already have slightly bad night vision so I wonder if it would get worse or stay the same.
I had pretty bad too... I would say after three months of it being pretty bad after the surgery, it went back to where I couldn't really tell a difference, so it might be worse, but I have adjusted to it. It won't get better. That is something to think about.
Also, with the new "wavefront" or "waveguide" technology, instead of just programming in a perscription to zap out of your lens, they actually can adjust for astigmatisms and other variations in your eye so that you can end up with better vision then you could with contacts or corrective lenses. I was lucky that my vision overall is better then the best corrected vision I could get otherwise.
also that the scar tissue mite be a problem later on when you need cataract surgery
I really don't know what scar tissue you are talking about... The eyes heal in a different way then other body parts. I was particullary concerned about this because I get very nasty scars and have excess scar tissue. As long as you don't have an auto-immune disease, then your eyes heal up just fine without any scaring. The only thing that changes is that your cornea is thinner, making it difficult to perform a second procedure if you get under corrected, but it does not cause any complications with future eye surgeries.
I still recommend anyone taking a look into it and understanding how the process works and how it will fix your eyes. It took me about 3-4 years to make up my mind and finally go for it, and you really want a doctor who is isn't going to take risk just to make a sale, you want one that is going to make sure you are a good canidate.