I tried Dimension Shellshocked's Survival Mode and feel a bit bummed. Many pickups with the exception of boss juice, temporary attack speed boost, temporary invincible taunt, and crystals are taken directly from the main game. There is no powering up or elementally infusing different attacks, no traps/weapons to use, and no health items except if a player is lucky enough to get one at the end of the level. There does not seem to be anything unlockable that changes how characters are played. The stages themselves are aesthetically random with factory and missing comic book panel ones having particularly annoying hazards. Worst of all, the crystals to progress seem to drop randomly with many tougher enemies dropping nothing at all. It feels half-baked.
As far as the new characters added are concerned, they are a mixed bag. Usagi's animations look awesome but he is slow and lacks power. Karai on the other hand is a surprisingly fun addition with awesome specials and throws on top of agile attacks that erase enemies, but has some awkward stances in animation frames. It is sad to see Usagi get the short end of the stick relative to the rest of the cast and will hopefully get an adjustment or mod.
Is it worth $8? I don't know... For everything good in the DLC, there is something bad.