We have three KIDFIX i-SIZE seats in different family vehicles and use them every day. For reference our son is 4 years old, a shade over 1m tall and weighs around 20kg. Here's our real world observations starting with the positives: Fitting the seat is pretty straightforward and should take you less than 5 minutes. That said, I got stuck the first time I did it because the instructions supplied by Britax aren't very clear. A quick YouTube search and 30 second video cleared up my problem. My advice is find a video of how to do it and don't bother using the written material supplied with the chair. Once the seat was fitted in the car, I was reassured to find the ISOFIX clamps are sturdy. When fixed into place the chair has very little movement in it. In my experience it can be difficult to release the ISOFIX clamps on some car seats, stiff mechanisms etc. But with the KIDFIX I-SIZE its easy to move the seat if you need to, and the release button is helpfully bright red so you won't miss it. Britax have also clearly marked on the seat where you need to feed the seat belt - as this seat uses the car's seat belt and not its own separate one. Family members who very rarely put our son in the car have said they find it easy and intuitive to use. The seat doesn't weight very much at all and is easy to lift in and out of the vehicle. Being lightweight also makes it easy and convenient to store if you need to remove it from your car regularly. Previously we had a baby and toddlers seat with a separate 360-degree heavy duty base and finding somewhere to store it all when we needed to use the back seat of the car was a chore. With the KIDFIX I-SIZE that isn't a concern. When researching car seats I thought the I-SIZE might be too big, or our child too small, but he fits fine and there's lots of room for him to grow with it. I can't imagine needing another seat after this one. It's easy to move the head rest up and down and can be done when the seat is empty or there's a child in it. We got the seat in black and the design is fine. It compliments the black leather upholstery in our cars and isn't an eyesore. The materials the seat are made from feel OK - neither super premium nor cheap - and the cloth is easy enough to wipe clean. Just recently our son slept for over 90 minutes during a long journey. The seat doesn't have much tilt adjustment in it because the back of the chair has to be snug against the back of the car's back seat for safety. I thought this might mean our son was more inclined to flop forward if sleeping, but this didn't happen once. Our son doesn't sleep a lot in the car anymore so options and configurations that allow him to do so weren't high on our list of priorities, but from our experience, if your little one is tired they'll be comfortable enough to take a nap in the KIDFIX I-SIZE without any issues. The only thing I'm a little disappointed by, and the reason I awarded 4* not 5*, is I've noticed that the cloth cover on the seat comes lose quite often. The cover is designed to stay in place by being tucked into the plastic frame. However, I've found that after regular use, the cover comes away on some of the corners and I have to re-fit it. It's not a big problem and is easy enough to solve, but for a ""premium"" brand, it shouldn't really happen at all. Overall we are really pleased with the KIDFIX I-SIZE. It is a high quality child seat that feels safe, is easy to use and maintain, and is competitively priced. I have no hesitation in recommending it.