Celebrations prior to that were even better for guests. You could win some cool prizes just going thru the MK turnstyles. I have a couple of non-winning "15 Years" prize tickets at home. I could even have a Tencennial t-shirt somewhere...
The 25th was the last great WDW celebration. The Millenium and 100YOM were good, but everything since the 25th has paled in comparison. I don't even need to mention any of the "anniversary celebrations" in the past 15 years...
And, I've always loved the "20 Magical Years" logo. One of the all-time best.