Droolicious

We have been using this product for two years.  Honestly, it's fantastic.  We've lent it to four families, all of whom have gone out and bought their own.  It makes the carseat schlep a thing of the past.  Now that our daughter is four, we don't bring the stroller with us anymore when we travel, but in a crunch, this thing is fine as a stroller. (Example:  We had to bring our carseat to get to a lunch date in a taxi in London, but afterwards, we're going to go to the London Eye, the changing of the guard, Westminster Cathedral... by the end, our daughter was riding around in splendor in her carseat.)  The two shortcomings:  The giant thumbscrews that you use to attach this thing to your carseat have to be turned about a million times.  It's easy - it's just more turning than would seem necessary.  The other thing is that technically, you must take it off your carseat for travel, but it's so easy that it only adds another minute to your trip.  We HIGHLY recommend it.  It's a great product.

ITA with the above, and add that if you're trying to decide between the sit and stroll and this thing, there's no decision.  This thing ROCKS THE HOUSE.  Your regular fantastic carseat with wheels as an adequate stroller (unlike the sit and stroll which is a crappy carseat and a crappy stroller).