Well I am only in to my treatment 7 days but so far so good! The first few days were kind of painful (totally expected) but nothing that Advil didnt help with. My teeth were obviously sore and my tongue/cheeks did get pretty irritated from some fo the edges on the aligners. I havent had any gum problems at all. Right now I am not experiencing any pain or irritation in my mouth at all. Most of the time I forget that I have them in. I love how clear they really are! No one notices them at all and I talk as much as I always have...a lot. I do have a whopping 9 attachments but my dentist must've done an amazing job of putting them on because they are really hard to spot (with aligners in) and dont irritate my mouth at all (when the aligners are out). I have a fairly long treatment time (33 trays top and bottom) as I am a more complicated case. I've read a lot of reviews here saying that Invisalign flat out cannot treat complex cases but I think a lot of that depends on your dentist/ortho. Find a good one as I believe that makes a world of difference! You have to have one who knows how to plan a treatment course to get you the results you want or to at least tell you that you are not a candidate for this treatment. My dentist is excellent and I'd recommend him to others all day long. He was very upfront about anything and everything involved with Invisalign including attachments, filing and possible refinement later in treatment. My dentist wasnt sure that I would even be able to use Invisalign for my treatment when I first came in but he worked hand in hand with Invisalign (for about three long months) to get the results that we are looking for. I am very confident in my dentist and my treatment plan so we'll see how it goes!!! I can already tell that my teeth have moved and that is the best feeling!!! Find a great dentist/ortho, be realistic about your treatment and do your best to hold up your end of the responsibilities (hygiene!) and you'll be ok. :) Invisalign isnt a easy or quick fix...but it sure does look nicer than traditional braces.
PS-If I run in to any problems I'll make sure to update my review. :)