I agree. I've never found Milligan very funny, but some of Monty Python is great. Unfortunately the hit rate isn't that high: perhaps a third of the show is really good, whereas (to my mind) all of Blackadder except the first season is very high quality. Obviously there's a lot less of Blackadder than MP, and the comedy is much more disciplined. The Monty Python films, especially The Life of Brian and The Holy Grail feel tighter and more consistently funny. Being silly well is difficult.
Some the cultural reference stumped me a first . The Skit revolving around Biggles . It wasn't till years later that I found out what that one was all about.