Victory at Stalingrad is paid DLC that's a part of the larger Turning Point update, which also includes new free multiplayer maps, the World Builder tools, four free commanders, and four premium commanders. The free stuff is great, so even if you don't want to buy more DLC for Company of Heroes 2, you will still find something new if you jump back into the game.
I really enjoyed the base game quite a bit, and it has added a lot of content since its release. It's also been patched up, balanced, and polished even further. Finally, the new content is here, and I can't wait to fail miserably at all of it.