From past experience these are poor quality car seats that do not offer as much protection as a Britax or Maxi Cosi car seat. We had many returns and I have also seen many come back damaged before they have even had to withstand an accident. I would also not recomend buying a seat without having it fitted into your car as many people do not fit them correctly and all car seats do not fit all cars.
It is a good idea to look at a seat which goes from birth up to 18kg because I have known 7 month babies grow out of their rear facing infant carriers because they were already 13kg!! Even though this seat goes up to 18kg it is in fact only rear facing up to 10kg which is 3kg less than most rear facing car seats.
Ideally children should stay rear facing until they are at least 2.6, but really the longer the better. In the UK most 5 point harnesses only go up to 18kg and booster seats only go up to 36kg. In other countries 5 point harnesses go up to 36kg and booster seats go up to 45kg which is obviously much safer and I don't know why we don't stock more of these in the UK. I think in the UK the best weight limit you'll get for a rear facing seat with a 5 point harness is 25kg which will last until approximately 7 years. Here are some to look at and see if they will fit your car:
There's a non-isofix one called the Be Safe Izi Kid X1 that goes up to 25kg aswell but I can only find the isofix version which seems to only go up to 18kg.
There's also the Akta Graco Cosmic Comfort S but I heard this one is only up to 25kg if used in the passenger seat. If you use it on the back seats it is only up to 18kg. I don't know if that's true for definite though so would be worth checking out just incase.