Yes, I had a very nice time during my October cruise (and I've cruised 6 pre-Covid DCL cruises, so I know what they used to be like). The main attractions are still there: beautiful ship, great service, characters (from a distance),
Castaway Cay, themed restaurants, great shows, etc. The kids clubs are more limited, but at age 3 your son might have been too clingy to be deposited for hours at the club, anyway.
There is also no way to know what May will be like: it may well be more back to normal at that time, but who knows? There is a welcome aboard experience in the atrium that is actually more close-up with the characters than the sail away party was, as only a small number of passengers are there at the time. Your 3 year-old will probably like that a lot, as he'll get good views of the characters there & probably personal waves from Mickey, etc.