By far the easiest adapter- you just click it into the stroller, strap in the corresponding car seat and go!
We bought our stroller after our car seat, so this attachment was the only way we could use the stroller for walks with our three-month old. I do love that this was an option (because I didn't want to wait), but the attachment leaves some things to be desired. First, the car seat doesn't always catch and click in well, so the safety strap is an absolute must. I'm not worried about my daughter falling out, but in my opinion it should click in easily without any question as to whether or not it's okay. Second, the side of the attachment where the two metal pieces come together scraped off one of the safety stickers on our Chicco car seat. Luckily it wasn't critical information, but this is not ideal. Finally -- and this is the biggest downside -- the stroller can't be folded down with the attachment on. This is a huge bummer, because it means we can't take it anywhere but in our neighborhood. I had no idea this would be an issue prior to purchasing, and there is no quick and easy way to remove it (it requires a screwdriver) so we have chosen to live with it. Again, I'm happy to have the attachment, but my recommendation to first-time parents (who don't want multiple strollers) is to pick a car seat and stroller together from the start, so you know they're compatible. I hope this helps!
This is easy to use and folds with the stroller which is a real time saver!!