Update: I was unfortunately not aware of Shamus Young's severe criticism of Fallout 3 available here to link in the original piece and I regret that. It dovetails rather nicely with what I've written and it's much better executed than my piece. I strongly recommend anyone...
Allowing myself a glimpse of hindsight, it was rather fitting that Grim Fandango was one of the last games released for the adventure genre until it... Well, if it didn't die, at least it was put into a serious coma where you need life support to even keep it breathing. And as it was, it was also one hell of a way to go, because this game is amongst the very best to ever have graced the genre.
The setting alone is so chock full of intriguing elements that it was almost worth it alone. With the manual giving us a description of the Day of the Dead tradition in Mexico, you get the feeling before you've even started playing that a real effort was put in to make this plot something different. And the expectatitons are filled almost every inch of the way. I'm not sure how they did it, but I can tell you that playing a character based on a papier mâché skeletion that lives in a film noir setting has never been as fun as this.
And the setting was, at least at the time, incredibly beautiful. While I'm not generally that interested in how technically good the graphics is, I know pretty creative design when I see it, and Grim Fandango's got it in spades.
Adding more greatness, there's a plethora of good background music, changing almost for every screen you visit at times. It never gets annoying, it stays where it should stay most of the time, and when it's time to pull it forward for a more direct job, it doesn't hesitate a second to step up to the plate (whatever that means. Non-US citizen, rememeber).
And to top it off, we've got a bunch of characters that, for all that they are skeletons, have more personality that 99% of living game characters. Voice acting is better than most other games I've ever played in any genre, including plenty of more recent games. If only game developers of today could look back to Grim Fandango and say "This is the bar, this is the standard. If we don't strive to clear it, we might as well just skip it." Unfortunately, that's not at all happening, and the gaming world is gloomier for it.
Speaking of gloomy, the increasingly darker plot is actually helping what is traditionally the weak spot in this genre: Replay value. Normally, that's often next to non-existant, but when you've spent a few weeks trying to solve the puzzles here and finally getting through it, you'll then want to play it again to get the whole story in one go. The gags may not be as funny the second time, but the rest is still good background music, still chock full of classic noir feeling, and generally worth a revisit so that you can see how some of the stuff early in the game fits into what happens later.
In short, there isn't much to complain about. The controls are a bit clunky, a few of the puzzles are, as they tend to be, a bit non-logical, and the pacing isn't always perfect. However, these things matters little when you get what was, in short, a pretty damn good adventure.