I'm four episodes in so far and if you're interested in the case then it's definitely worth a watch. As with a lot of Netflix shows there is a lot of filler in here to make it stretch to more episodes than is necessary, but I guess that trend isn't going away any time soon.
Episode 3 and 4 is where things started to get more interesting as the focus begins to switch more towards the parents' involvement etc.
They show the footage of the blood/cadaver dogs searching the original flat, another villa the parents stayed in and also the rental car they hired. For some reason I found the footage really unsettling, maybe the reaction of a dog is the closest we'll ever get to knowing what really happened.