I have this carseat for both of my kids. My son is almost four and we had him rear-facing until he was 3 1/2 - he's still small, only 30 pounds, but he was definitely ready to turn around. I like that it has such a high weight allowance for rear-facing and that it seems really comfortable for your child.
Since we've turned it to forward-face, it's been just as great. We can use it until my son is 60 pounds (at this rate, he'll be 15) and the height allowance seemed really great as well. I love the air cushions on the side of his head - they make me feel safer if we were to have a side impact.
My daughter is only 7 1/2 months, so I haven't switched her to a convertible yet, but I'm sure she'll love it as much as her brother has!
The only issue that I can see is that it leans back really far when rear-facing. We have a Honda Element, so it's not a problem for us, but it would be a tight fit in a car.