In version 7, I've noticed when you highlight a vector layer (that is nested in a GROUP) and toggle the layer visiblity icon (the 'eyes' icon) the layer does not switch on and off as in version 6.
If you highlight the GROUP layer and toggle the visibilty icon of the same VECTOR layer it switches on and off correctly.
It's odd that this function has been changed since version 6 and it confuses me when I have several layers and I'm using the toggle visiblity icon to find a specific vector layer in a group.
Is this a bug?
I too am shocked by the number of bugs and problems I've discovered in only a day of playing with the new version. The switch layer interpolation problem is also a huge problem. I'm tempted to get a refund and maybe update sometime later when (or possibly if) they get these problems sorted.