Well, yeah, positioning is always going to be critical whether you're talking about traditional speakers or inwalls or whatever. And I mean positioning in all three planes, and relative to all the other planes in your house.
The problem with any built-in speaker is that it's almost impossible to know exactly how everything is going to sound until you get it installed, and - by then - it's too late to make positioning adjustments practically.
The room is pretty important, and you can't really use trial and error to adjust the relationship between the room and the speakers if you are using inwalls.
