As much as I love Blood, the version of it that you can buy these days has one glaring weakness, and that's the extra episode Post Mortem. While Post Mortem adds some interesting new enemies to the game, its levels are not particularly well-designed, and it's quite difficult for all the wrong reasons. The final boss level in particular is quite a slog - you fight several copies of the same new enemy, who can basically one-shot you with an AoE attack that has unclear range. They also have a ton of health, so I hope you brought Tesla Cannon ammo. It's not a bad pack of levels, but it's definitely the worst content in the game, hence this rating. If you love the first four episodes, check it out, but otherwise check out Death Wish instead.