There is a way to securely snap the car seat on top of the stroller, but I ended up not using that.
When my baby was smaller, I carried the car seat as a basket. When he got bigger, I removed him from the car seat and sat him straight on the stroller.
By the way, if you use both together, you can have the baby completely covered by combining the cover of the stroller with the cover from the seat.

The car seat seems secure and protected on the sides.
The latches have very positive clicks when they close. It is very difficult to install it "halfway" - it is either all or nothing - which is very good to prevent a parent from half-heartedly attaching the seat to the base.

The car seat becomes very heavy when you have a baby in it, even if the baby is only 8 pounds (~4kg) or so. My wife can't carry it by herself. She has to resort to the stroller, which is also a bit heavy for her to take in and out of the trunk.

The stroller is solidly built... Read more