Well, first and foremost, it's far too much dough for how much of a PITA it is. It's just not, IMO, anything special.
It's a borderline nightmare to install with a seatbelt. Yeah, most people have LATCH, but a lot of people prefer to put their newborns, especially first-borns, in a center position, which, usually, isn't equipped with LATCH. The more complicated the install = higher chance of misuse.
It doesn't fit newborns especially well and I've seen a lot head slump going on with newbies. It tends to be, or appear to be, a little too upright.
The handle MUST be down when in the car. Minor, maybe, but still annoying to me. And, again, it falls under one of those areas where parents aren't going to realize it (because, in real life, not many people read the manual cover-to-cover and file away mental notes like us freaks) and just not do it.
The puzzle buckle doesn't really bother me. But, maybe it would if it were a fulltime, everyday thing.