It's something of a weird beast in that it's supposedly system neutral, but that system neutral is obviously an older school D&D. There are levels (this is for levels 1st to 4th), but instead of hit points, there are life points. Armor class is given as an equivalent to armor, ranging from leather to field plate, but with some oddities, like bronze platemail (which is just the same as banded or splint, which it uses elsewhere). With that said, there's very, very, very little treasure, and for that matter, not much motivation for the adventure in the first place.
The dungeon itself is well detailed, but there's really not a lot of variety. While it's called a "sunken temple", really it's a crypt, so almost all the encounters are with skeletons, or skeleton like creatures. There are a couple of puzzles. But in either case, there's really not a lot of motivation for the players, as there is almost no treasure, either actual wealth or cool magic items to find. Much of the exploration is just to push forward the plot of redeeming the dead dude's ancestor.
As such, there's a lot of "boxed" text in this, that is, text meant to be read to players. Usually broken up with the phrase <players react> to know when to let players actually, well, play. While I do not generally use boxed text, I do not really mind it, as long as it's short (2-3 sentences). It's really overkill here, as I would say most of the product is boxed text. Even that could be overlooked if it were a compelling story (like say that of the original Ravenloft), but here it's hard to care about the guy's ancestor, since he seems kinda whiny.
The other thing that really sets it apart from other modules, and is advertised a feature, is it's handling of light. Most rooms have added descriptions when players use a better light source. Beyond that, it constantly features "treasure" that consists of light sources (torches and oil). To make this easier to handle, it includes several tracking tables to make keeping track of how long the light lasts easier.
are separate combat maps (as Pay What You Want) that might help in this regard
A lot of work went into The Sunken Temple of Chloren-Var, but I think it's held back by it's somewhat strange design. Are there people who find tracking light meticulously to be enjoyable? I'm sure there are, but it's something that gets handwaved in most games. And while I think read aloud text can be helpful, I think there's just too much here to be easily read to players, or to be listened to by them. I really can't help but think that this should have been an old style computer text adventure, like Zork.