Will the commentaries spoil anything for someone who hasn't played the game before?

As a general rule I never do a first run of the game/first watch of the movie with commentaries on. While being informative, it's a bit distracting and can break the pace, not to mention be potentially spoilerrific.

The commentary in this game only touches certain elements of the scenery at the press of the Z button, so I don't think it should spoil the plot. What it can spoil is puzzles and their solution, as the devs talk in-depth about them.

I didn't listen to the whole commentary myself so take this info as it is and just listen to it on the second playthrough.

why would you listen to the commentaries before you even play the game? no offence but that is just feckin stupid.

Because it would probably be closer to ten years before I replay this game (there's not enough time or motivation to replay it right away just for the commentaries) and I'm interested to hear what Tim Schafer has to say.

isn't the actual plot of the story more important? I mean if it's this big a deal why not just watch a video of it?! Sounds like you wasted your money really.

The plot isn't spoilt at all. I'm near completion, and I have listened to every commentary on route. There have been 2 where they have made the solution to the problem a bit more obvious than it would have been.

All in all, I think they did a great job.

Yes, from what I've seen, it has a lot of potential spoilers. You should never listen to the commentaries on the first run.