I've been taking it for 10 months, and yes, I did have weight gain from it, but it appears to be edema; though I have no idea how much I gained b/c I never weigh myself. But I definitely went up a size or 2.
I do not have constipation from it, nor do I have dry mouth. What is weird is...I normally have a very dry mouth, but for some reason, the Lyrica helps my dry mouth. For a while, when you first take it, you might feel strange, kind of spacey, or feel like your brain is out of focus.