Summary: While the Sirona is a good idea in principle it is let down by poor execution. The buckle for example is fidly and so when you have a squirming toddler it makes it hard to buckle the child into the seat. Also for some reason it's difficult to tighten up the the shoulder and lap straps, yopu really need to pull up on strap with a lot of force in order to get a good fit on your child.
Pros: Comfortable Machine washable covers Seems very safe Can be either front facing or Rear facing Easy entry and exit for child due to swivel feature
Cons: Poor design Can't clean base and swivel mechanism easily Poor buckle design Straps very stiff to tighten properly Base material wears very quickly