"is there any thing wrong with using PVC?"
I asked that same question of my brother, who is a mechanical engineer. He gave me excellent reasons for not using PVC. I sure wish I could remember what they are.
It seems like one reason was that it does not take vibration and movement nearly as well. And isn't standard PVC unacceptable for the hot water supply (somebody please help me out here!)? I believe it also has a much higher elasticity in case it freezes.
As a practical matter, the PEX is easier to snake around corners and so forth without using connectors. If you buy it in coils, and bend with the coil, I think the radius of a corner can be as little as four times the diameter - so a 1/2 inch piece of PEX can turn on just a two inch radius!