Short but gold. It's more of Blood West, with just enough interesting new mechanics to make it fresh again but not so much that the base formula is lost in the process. The new enemies are challenging and force you to be more aware through smart design, as opposed to just pumping numbers - for example, one of them hides in plain sight by sitting on treetops and tall cliffs. It's not difficult to spot them and the enemy itself is nowhere near as dangerous eg. a Skin Collector, but until you learn to look up and listen for their distinctive sounds, you'll keep getting ambushed by them - perhaps at the worst of times. New weapons are generally quite good, both in power and in design - the staves in particular allow you to shake up the experience quite a bit, one of them allowing you to send a creature berserk and turn on its own allies. And the final boss of this chapter has an awesome design, only rivalled by the boss of main game's chapter 3 - blowing both the blood tree and the cursed giant out of the water. It's even foreshadowed, if you care to read the various notes you'll find scattered throughout the world - THE BLACK SUN DEVOURS .

The expansion has two distinctive flaws though. First being the length, as it's roughly as long as any other chapter and I just wish I got to spend more time with its new weapons and enemies. Not that big of a deal, but by the time I got a hang on just what I could do with some of the weapons and how to deal with the most challenging enemies, it was over.
The second is the map, and that is much more serious. The base game had three main environments, one for each chapter - desert, bog and forest. I'm not sure whether I like desert or forest more as both of them have an amazing main theme of an open area bathed in moonlight, and enough variety to ensure it doesn't get monotonous. The bog, however, is the worst by far - while it technically has the same variety as the other environments thanks to emphasis on human settlements, the visual variety of the surroundings isn't all that significant - and that's made infinitely worse by the omnipresent fog obscuring every corner of the map. Whereas other chapters are bathed in moonlight, creating ample opportunity for shades and shadows to give it plenty of atmosphere, in the bog there's none of that. There's barely any shadows, silhouettes of enemies and buildings blend together and the texture work that gave some enemies (like the common Animated Dead) more identity that you'd expect from their basic designs has no chance to do so here - "thanks" to the bog's darkly fog.

• Creative and grotesque enemy designs (Vessel, Strix and Terror Eye to name just a few)
  
• Enemies pose a good challenge without becoming bullet sponges thanks to clever mechanics (Lemures, Tormentor, Vessel, Terror Eye and Wraith Wolf especially)
  
• Interesting unique weapons that avoid "+5% x/y/z" formula
  
• Terrific final boss with some nice foreshadowing
  
• The story of the expansion cleverly tied into that of the main game
  
• More NPCs to interact with and give the setting a sprinkling of flavour
  
• The Tears in Reality provide much needed environmental variety

• It's The Bog, Again. We may never escape The Bog.
  
• Somewhat short at just one standard-sized chapter
  
• Most artefacts and non-staff unique weapons are still boring "+10% chance to do something that doesn't matter" or "+5% that doesn't make a difference"
  
• Three poorly designed enemies: one from the base game (Skin Collector) and two new ones (Ravager, Abyss Walker)
  
• NPCs look bad, both due to the model and the stiff animations

As long as you're fine with the two major cons I mentioned - that being the length and The Bog, Again - the expansion is well worth your money. It's got decent amount of content with enough mechanical twists to keep it fresh and interesting. Enemy designs are more eldritch and grotesque than ever before, reaching a new height quality - and it might be worth getting the expansion just to see those.