My daughter is 14 weeks old and has been using her Bumbo Seat for about a month now.
She did like it, but only in 5 minute increments.
We got the Bumbo Tray for the Bumbo Seat and now she doesn't want to get out of her Bumbo Seat! Yesterday was her new record of 30 minutes. The Tray is right against her belly which I think gives her a nice snug feeling. You can see the excitement in her face as she reaches for her toys on the Bumbo Tray.
If you get the Bumbo Seat, the Bumbo Tray is a must have.