Most of the LotFP publications are adventures or settings, few being sourcebooks (like Vornheim for city adventures or The Seclusium Of Orphone for creating mages' towers). LotFP doesn't believe in traditional monster books, as its weird fantasy philosophy is, that each creature/monster encountered should be unique instead of just something out from monster manual. Slügs is a compilation of monsters - slugs in this case - but they are all unique and individuals. Or that's the impression the text gives. You don't meet 10 "muscle slügs" (yes, they're there) guarding a treasure in a dungeon.
There are 16 different slügs in total, each different. Generally the aren't just meatbags and hit points for player characters to grind for experience and loot, they all have a gimmick or two - but the gimmicks are not stupid. Well, some of them are, like the christmas slüg what you get presents from if you're lucky, or breakfast slüg which is a slimy bowl of cereal. These slügs can be a big part of campaign, and a quest to find, for example the doctor slug to be found to cure horrible wounds and damage an adventurer party member has suffered. Some will make a quest, like mentallo slüg, who knows the future and wants you to prevent something horrible from happening. Some of them just have an effect, like sluggish slüg. But for those who want to fight horrible monsters, there are more traditional slügs like the vomit slug.
There are NSFW work included, but the quality of drawings is great. Kelvin Green's (Forgive Us) slüg drawings are great and he has captured the different qualities of the various slügs very well. Yannick Bouchard's inside covers are his usual great quality. And Rich Longmore's cover that expands to the back is very colorful.
Slügs was a fun read. There are many different slugs from which almost any Game Master can find something to throw into their campaign world. Many of them are humorous, some even stupid, but most of them are easily usable (the humorous and stupid depend on the players and campaign, rest don't that much). Even IF Slügs was just a big joke, you can use it without making your campaign just silly.
For the price of less than a dollar, when you order anything from LotFP strore, there is no excuse of not including this to it. I say, go get it!