We happened to get some free tickets to ride the High Roller on a recent trip to Vegas. We had a busy day and night with shows, gambling, and sightseeing, so we didn't make it to the High Roller until around 1 am. This was actually a great time to go as there were very few people in line. Our group had six people and a baby, and we wound up getting a pod with us and one other person. This was great because we were able to wander around the pod at our leisure without worrying about getting in someone else's way or photo.
The ride lasts about 30 minutes. There's some seating on the inside, but not a lot. It was fine for our small group, though we didn't sit too much anyways. It revolves at a slow pace, so you can't really feel the movement. The views are nice, though I think you get a better view from Mix Lounge at Mandalay Bay. It's a cool one-time experience. However, if I got free tickets again, I would probably give it another go.