Wait for Reviews
It's tough to wait for reviews of the full Call of Duty: WWII Season Pass and each DLC before you buy, but if you read reviews of the second DLC you will at least have a pretty good idea of what Sledgehammer games is capable of.
With the third Call of Duty: WWII DLC out in a week, you can make your call once it arrives and be pretty sure of what you are getting. Yes, there is another map pack, but first two DLC set the tone for the rest of the releases, and DLC 3 looks to follow that theme. Occasionally DLC 4 goes a little bit out there in previous games. With WW2 as the setting, we expect things to remain pretty grounded throughout.
Once you can read reviews of the new maps, you can make a call and buy or skip the Call of Duty: WWII Season Pass with all the knowledge you need.