A neat, if uneven, collection of necromancy- and undead-related additions for 5E. Breaking it down section by section:

• College of the Dirge: An undead-focused bard subclass. Overall this is pretty solid, but their Dark Virtuoso ability is overly complicated.
• Circle of Blight: A druid subclass with undead-like abilities. Neat features (though Blightform may be too powerful for 2nd level), but I don't know about the theme of this one, since undead are pretty anti-nature. (Also, the official 5E Circle of Spores is a better implementation of a decay/undead druid - though it has something of the same theme problem.)
• Soulblade: A fighter who can steal the essences of creatures it has defeated to enhance their attacks. I really, really like the concept and mechanics for this one... but it just doesn't feel right as a fighter subclass. (Maybe it'd be better as some kind of hexblade warlock variant. Or just as a magic item.)
• Blood Magus (not "Bloodwalker" as in the DM Guild blurb): A wizard subclass with features centered around blood and injury. This is particularly uneven - Level 6's Fueled by Death seems pretty strong, while Level 10's Inured to Pain seems underpowered. And Level 14's Bloodwalk is just gross. Definitely not my pick of the litter.
• Spells: Four generally good necromancy spells, including one lifted straight from Diablo (Corpse Explosion).
• Magical items: Four items, all fine, if pretty macabre. (Though it's "Death's Letter" and not "Bloodletter" as in the blurb.)
• New necromancy rules: Probably my favorite part, this expands on the options for undead-creating spells, including the ability to summon more varieties of undead and adding enhancements. The only minus with the latter is that they don't tell you how the new features might adjust a creature's CR (important for fighting NPC necromancers); guess you're supposed to figure it out on your own.
• Appendix A: Guidelines for turning any creature into a zombie or skeleton, and a bunch of pre-made zombie statblocks (for use with the new summoning rules). Very useful and convenient.

The presentation is generally pretty good, although there are some typos here and there.

Overall, the class options are interesting but might need some adjustment; the spells are solid; the new magic items are fine but kind of niche; and the alternate undead rules and statblocks are very useful (though you'll have to recalculate any CRs yourself). The good parts of this product make up for its issues, so it's definitely worth buying to bolster your death-related options.