I bought this almost as soon as I found out I was expecting and it's been fantastic. I drive a lot with work, both my own car and the company van. With it's quick release buckle it's easy to swap to another vehicle in only a minute. The same applies if you switch from being the driver to a passenger.
The strap for fitting around the seat is adjustable, so will fit a lot of different seats. In my hatchback, if I sit in the back I have to choose the smaller seat... basically where the back seat folds down it does so in two sections, one as wide as one seat and one as wide as one seat plus the middle section. The strap isn't long enough to go around the larger section.
Finally, I'm quite slim and normally a size 10, so my thighs are not overly large. This means that the centre section of the belt that pulls the seatbelt down, only just pulls it down enough. In an ideal world it would be great if this was adjustable so it could be pulled down further or let out slightly depending on a person's thigh size. On the other hand, the way it is does pull it down just enough for me and certainly prevents the seatbelt riding up over my bump, so it does the job! It would just be something to consider if you are very petite.
It's quick to get in and out of, and feels very secure and comfortable when driving. It's not ideal however if you're wearing a skirt as you'd have to pull the skirt right up in the middle. If like me you don't wear skirts very often, then this is a good choice as it's much more snug and secure than others I've seen.