Definitely recommend that you get this, even if it's the only DLC you get. The levels are challenging (plus you get three new Endless maps) and the new enemies a fairly unique mechanically (I'll let you figure out what they do for yourself). Though not for the faint of heart when it comes to singleplayer nightmare, victory (and five skulls) are still possible. So to be more specific, here are some pros and cons from my playtime.
PROS
-Two new monsters with unique mechanics
-Three new campaign levels
-Three new Endless mode maps
-A new weapon (Dwarven Missile Launcher)
-A new trap (Spike Wall)
-A new trinket (Guardian Trinket)
-Two new character costumes (Backdraft for Warmage and Skull Ninja for Sorceress)
-Needless to say, everything above looks great and works well, being fairly balanced.
CONS
-Though not necessarily a complaint (I do love a challenge), the last two levels were quite obviously designed around the co-op game mode (which is great). Unfortunately, this means that they can be extremelly difficult in singleplayer (at least on Nightmare difficulty). Their not impossible just difficult. You have been warned. Don't let it keep you from getting this DLC, though.
Other than that, nothing else comes to mind. Get it, play it alone, play it with a friend, and enjoy! And with the new cosmetics, you can look snazzy while doing it.
izigame.me
It may take some time when the page for viewing is loaded for the first time...