I've had this car seat (in red) for my 4yo for about a year. It's a decent seat, fairly well-padded, and my daughter is generally comfortable in it. The price was good, it's not too huge, and I'm fairly pleased with it.
--Price: if you can't drop over $200 on a car seat, take a look at this one
--Fabric: easy to clean, doesn't snag
--Chest clip: initially I didn't like it, but once I figured out how to get the right angle so I could undo it easily, I was glad it was more difficult than the previous convertible car seat my daughter was in because she can't undo it!
--Seat and head pad: nice if your child falls asleep in the car seat frequently and the seat pad is nice because it is easy to take out and clean. That said, I don't know if they are worth the extra money. My daughter is no longer using hers.
--Latch system: I'm sure there are others that are easier to install, but I got mine into my '08 Odyssey securely after about 10 minutes of old-fashioned elbow grease. I wouldn't want to move it frequently though. I doesn't move at all near the points of attachment, and safety recommendations say no more than one inch.
--5-point harness: As one reviewer said, it is one continuous loop of webbing, but so is every other economically priced car seat I've ever used (and after 4 kids, I've used quite a few). It's not hard to slide it to make sure it's even. As to the slack being up front, it's initially odd, but it makes frequent adjustments easy.
--Accessories: They do fall off easily. They are also easy to reattach. I install the cup holder for long drives for my daughter and just have it near the door so it's not getting knocked off as the other kids pass by the car seat on their way into the back. Don't buy it for the accessories--they're probably about 75 cents worth of fairly cheap plastic, but they do the job if you're willing to reattach them when you actually need them there.
--Learning curve: Yep, like every other car seat I've had or used (numbering over 10), you have to figure out just how to use it until it becomes easy. Give it a week or two, and you'll have it down.
--As a belt-positioning booster: Lousy! But hey, you can get a really great one (Graco Highback Turbo Booster Car Seat, Spitfire) for about $40 (less on sale or in warehouse clubs). Even buying both will save you money over some of the more expensive options.
As for the IIHS not recommending this seat: absolutely true, but only when using it as belt-positioning booster because it doesn't give a good fit with the vehicle's lap and shoulder belt. Just look up the review; it's easy to find. I have to say that I agree with them. If you're looking for a belt-positioning booster, save yourself some money and look at the ones on the IIHS top picks list. With the 5-point harness though, this seat is fine and can accommodate a fairly wide range of heights.
I'd give it 3 1/2 stars if I could, but hey, nothing's perfect.