This is a fantastic product. Easy to attach and remove. We bought this after buying a trailer and a back fitting bike seat.
Pros 1) Better than trailer/rear seat because its actually fun! I did a 3 hour bike ride with my daughter over Bay Bridget all the way to Tiberon (long for me). When we finished she wanted more! Oh, by the way, I stuff a peanut butter sandwich in her hoodie and some wipes. She can eat her lunch without me stopping!
2) You can actually talk with your child as you ride. Great for multitasking... bonding + exercise. Also, I'm afraid my kids will beat each other up if they are in the trailer since they are so close in age.
3) Ease of use. Easy on and off. Seat can come off the "bracket" that is attached. Easy to get her in and out too. No knee banging. Also works for bikes like our mountain bikes that couldn't fit the rear seat.
4) Flexible. works for my 10 month old and my 2.5 year old. She is only 25-30 pounds and about 3 feet tall. Height wise she fits. I need to get another one so we can all go together.
5) Cool :-) EVERYONE stops us and asks where we got it. I really feel sorry for the kids in the trailers... or worse in the rear seat pressed up against Daddy's butt with a view of daddy's sweaty back.
Cons (not really) 1) If my daughter moves her head too much sometimes she knocks me in the face. I need to snuggle by one side of her face. I guess if I was taller (I'm only 5'2" my arms would be longer and I'd have more clearance). My husband at 6'0" has no problems.
2) Seatbelt not great... sometimes it rides down her shoulder. Worry about her flying off but I'd worry more if she was in the back. At least I can see her. There is a lap bar though... make sure it snaps in place.