I had the Fisher Price infant car seat for my 1st 4 sons, and just bought the fisher price one for my 5th son. The thing that makes this seat great is the carrying strap-- you carry it on your shoulder kind of around your neck, so it rests on your hip, and leaves BOTH HANDS free!
I am not kidding when I say that EVERY time I have taken him out in it and carried him around, whether it be into the store when shopping or to the doctor's office or whatever I get AT LEAST 3 comments on how nice that carry strap is, "I wish I had that on mine!" The seat itself is actually lighter than many of the other infant car seats, too.
On thing to keep in mind: If you get a convertible seat (rear facing for infant and forward facing for toddlers), you don't have anything for your infant to sit in when you bring him/her in places, whereas with an infant seat, you always have a seat for them (without having to wake them up too).
The other thing we discovered in MN when we brought our 1st son home from the hospital in the convertible seat was that it was hard to get him in and out of that kind of seat quickly in the cold. We went out the very next day to buy an infant seat so we could carry him out to the car already buckled in and covered up and just buckle the seat into the car seat belt (now with the new model, we just click it into the base -- even quicker and easier, no fussing with belts in freezing weather!).
HTH!
Kristen