Does anyone have any opinions on The First Years "On-The-Go" Booster Seat?

I found it at K-mart yesterday. It's a really compact booster seat which looks very much like a little child's lunch box. It's easy to carry along. The seat is made of nylon material, much like that used in the child carriers. So the material is easy to clean. The seat self inflates from 2 inches to 4 inches for height adjustment. There are 2 straps which secure the seat to a chair. The child is strapped to the seat with an adjustable seat belt. I did buy it and tried the seat with my daughter at hgome. She seems to like being in the seat. And she seems to be quite securely contained in the seat. My husband's concern is that our daughter might outgrow the seat quickly. I did not see an age limit on the box ... except "12 months and up". Although my daughter is only 9 months, she seems to fit quite well in the seat.

I would like to know from anyone, their opinions on this product before I fully commit to it. Should I get a different booster seat? IF so, which booster seat is good and easily portable? Any suggestions?