It looks (to me) as if it's intended to be used inside the sleeping bag. The holes wouldn't compress the bag's loft and you'd be a bit warmer. I admit that I've not looked in a while but the reviews were good when I was on the look to replace my thermarests
The breaths to inflate are accurate (providing you have normal lung capacity and function). The valve may have changed but the one on mine is twist and pull to open, push and twist to close and lock. Other brands are likely just as easy to use and nice and secure in use.
I looked at the Inertia part of the range but plumped for the V purely because I'm a side sleeper who tends to fidget when asleep. Not knowing how the Inertia would react, I played safe
With hindsight would I risk it and go with one of the Inertia range? Probably, yes
(This is not to say that I'd enjoy it in use, just that I've been impressed by the V mat and the cush
). Sometimes you have to be the first to try something and be the point where it all started ... or fell
???