It's up there with Mario 3, ISS Deluxe, FFVII and MGS 1 as one of my favourite games of all time.
I know it sounds premature, but as you said, it's massively engrossing. Be it aesthetically or whatever, there's always something that gets your interest. The relationship between Joel and Ellie, for example. The way it starts and then progresses, is just immense.
The modern gamer is hugely restricted to on-line, unfortunately. But all the while juggernauts like FIFA and CoD are dominating the market, others will follow suit. I'll bet your cousin plays these almost exclusively? That's not me having a go, BTW, as I batter them myself!! But for a game to stand up like TLoU has for story etc, is nothing short of superb, IMO.