The game has not aged gracefully; not in subject matter, plot, level design or gameplay. I hesitate to call it a "product of its time" as it was in fact preceded by games such as Half-Life and Kingpin, and was released mere months before games such as Halo, marking it as fairly dated, even for when it was new. The years have not been kind, and merely accentuate all of its flaws. Mostly linear levels, a 90es VHS bargain bin plot, mediocre gunplay and a gimmick (gore and localised damage) that wears its welcome thin much faster than expected. Nostalgia is the *only* reason to play this today. If you're a new-comer, you will likely not have a good time.
Mostly due to it not being the only diablo not available anywhere else for literally decades, and a historic artifact - it's been surpassed, but still has merits. In short, buy this if you've played it back in the day. If you haven't, you likely won't appreciate it and will possibly regret your purchase. It was a trailblazer back in the day, and today it might blaze the trail still for other, similarly-licenced games in finding their way to a digital re-release. Minor quibble, adding the Hellfire expansion would have been nice.