The National Highway Traffic Safety Administration (NHTSA) tests child car seats for ease of use (including assembly, evaluation of labels, evaluation of instructions, installing featues, and securing the child) and assigns an overall rating.  This is very helpful when deciding on car seats.  I would not rely solely on reviews when deciding on a car seat.  All children are shaped differently, so it's best to pick a car seat that fits your child best.

These car seats received really high reviews:

1) Infant Seat: Combi Centre DX ($140)

2) Convertible: Recaro Signo ($289)

3) Forward Facing: Safeguard Child Seat ($400)

4) Combination: Safeguard Go (FF) ($200)

5) 3-in-1: Eddie Bauer Deluxe Convertible 3-in-1 (B) ($200)

Safety 1st All-in-One (B) ($150)

6) Booster: Compass B510 ($90)

You can go to www.nhtsa.gov for find reviews on hundreds of other car seats.