The Onboard is actually one of my favorite seats. I miss the higher-end versions they used to make (the one I had for my girls 10 years ago had a lock-off on the base and a really easy to use height adjustment system; but it did cost more). But I work with the current models on a regular basis, and I still like them quite a lot.
Installing the no-frills base is a little more tricky than on some of the more expensive car seats with more installation features; however once you get it installed it usually stays there and soon its quirks fade into memory. For day-to-day use, the carrier itself is very nice, comfortable, roomy for the child, offers a great fit for a variety of sized infants from 4 lb. preemies to 20+ lb. pre-toddlers. Average-height children may make it to nearly 18 months old in this seat. It's easy to use without any weird and confusing "rules" to follow, which sometimes plague the higher-end seats with more features.
If you have any questions or concerns about its use, post here. It's a seat most of us technicians are very familiar with and should be able to help with any problems you might run into.