It was lonely at first. I was there for a year or so... a whole school year. I missed my family and friends and my fiance. But I really really enjoyed it. I made really really good friends, I felt very independant, I had a ton of fun, I learned a lot.
What I noticed with the people who studied abroad for one semester is that while they had a good time, they didn't seem to experience as much of the culture. When you're there so briefly you end up partying a lot and travelling so much that you never really get to the part where the novelty wears off and you're just living life.
This is a good thing and a bad thing... you probably won't get to the stage where you're importing peanut butter (British peanut butter is bad. Just awful. My friends said they hated Peanut Butter and then we discovered it wasn't that they hated peanut butter, just British peanut butter! ), Macaroni and Cheese, and complaining because nothing's open after eleven.
I say go for it. I think you'll have a ton of fun.