Going solo in December. My third consecutive solo trip and WDW trip in the past three years.
Previous two trips spent a week, and this trip six days.
Did I get bored going solo? Heck no! In addition to WDW, spent time at Universal and SeaWorld. Just like WDW, Universal and SeaWorld cater to single folks like us.
I abused the single-rider line at Everest, Test Track, Mummy and rode Kraken 10-12 times in an hour by just raising my hand and saying "single rider!"
As for the experience at WDW, SeaWorld and Universal, it's the same as if you were with a family or with your significant other or with friends.
Best thing, nothing to tie you down. You go and do what you want to do and see, and sometimes throw your plans out the window and turn on a dime.
Loved my two previous stays. Did four parks in one day, taking advantage of extra magic morning and evening hours, and finished my evening way late at night at Pleasure Island and the now-closed Adventurers Club and Mannequins Dance Club.
Enjoy!