I was on lexapro for about a year. It took a bit over a month for me to feel any effects, so be patient, but once it kicked in it was very effective. I did have to up the dosage every few months. The biggest positive for me was, at times, experiencing social situations without anxiety and learning how I could be. I became more consistently positive. I didn't experience any real side effects, except I did put on some weight. Also, my dreams were less vivid and I felt less creative.
I quit taking it before my doctor and therapist wanted though. I became frustrated with my progress and felt I went as far as I could go with them. I think it's important to face your anxiety and be able to rely on yourself. I'm not a big fan of pills anyway, and didn't like feeling sedated and somewhat artificial. But if you're in a bad place, I wouldn't hesitate, sometimes we need all the help we can get.