I love Nabokov. In fact, I named a stray cat after him who has since abandoned me. Or I, him. If you want a more approachable book of his to start off (pale fire is tremendous but daunting) I would recommend Laughter in the Dark. It is short and moves effortlessly. The characters are charming and evil. The plot reads like a suspense thriller. It is a wicked, wicked delightfully wicked book.
Anyways, if you've seen my cat please feed him.
I suppose I don't really buy the premise put forth from either direction; I don't buy that it's possible to be present while doing something else (for me anyway) AND I don't buy that this is gonna be immersive. I'm not stating these things as claims; this is just my reaction to the app store copy.
I did buy it and love it though. What really works for me is as a way to hang out with my kid when she's doing her own thing. I want to be available to be present at a moment's notice.