Isofix seats are designed to be easier to fit than those which use seatbelts.
However, they can be significantly heavier and more cumbersome than seatbelt designs, and so harder to manoeuvre into place.
Depending on the design of your car's seats, it might also be tricky to locate the bars which the Isofix connections clamp onto.
It's also worth bearing in mind that Isofix seats often come with legs which extend down to the floor of the car. They can take up quite a lot of space, and might force you to slide the front seats forward and sacrifice legroom in the front of the cabin.
Once you've read a seat's instructions, or been shown how to fit it by qualified in-store staff, seatbelt designs really aren't that difficult to use and are no less secure. They're also a lot cheaper than Isofix designs.
At the end of the day you must try a seat out in your car before you buy it one of our 10 commandments which you can find on the next page.