Personally I am eventually going to buy all of the dlc's but that's only because I want to fully complete the call of duty series. If you don't care about getting 100% in games than I wouldn't. These maps are not very good and don't fully show off how fun zombies can actually be. The ee's in my opinion based on what I have played and seen are much harder than other zombie maps and take a lot more work to get done. Of course that's just what I think and at the end of the day it's your choice on what you want to do.
Hope this helps