2nd Ed is one of four versions of the game I've played really extensively (with BECMI, 3e, and 5e being the others). In terms of hours of play, it's probably second only to 3e. (In terms of years, it's third - 3e still has the crown, with 5e second.)
I had a hell of a lot of fun with that edition! That was the edition where almost all of my formative RPG experiences took place, it was the edition that used for the first of my "great" campaigns (there are four campaigns I count as my very best RPG experiences over the years - one in 2nd Ed, one Vampire, and two 3.x). And so many other games, too, with so many friends.
But... I wouldn't return to the edition now. It's not that I consider the mechanics bad, per se, but there's enough in there that would just bug the hell out of me - these days, if/when I return to D&D it will be 5e or one of the near-clones (not that those don't have their own rough edges!)
In terms of products, I find myself bitterly regretting some of my purchasing choices: I invested heavily in "rules" books (the "Complete X" series, the "Players Option" series), and in the settings in a very wide but very shallow manner - in retrospect, I wish I'd instead invested deeply in one or two favourite settings (okay, three - Spelljammer, Dark Sun, and Ravenloft, in that order) plus the "Historical" series. Looking back, those settings are the real legacy of 2nd edition (not just the three I named - the others too).