We were there for nine days at the end of Jan last year and absolutely loved it. The weather was perfect for us, but we are from PA and weren't at home shoveling snow so were very happy. If you live in a warmer climate you might have a different perspective. There were plenty of days in the 70's but mornings and evenings could be cool. However I'm going to defer the to person who's lived in Orlando for 20 years above for advice on the weather!
We were quite pleased with the crowd levels. They probably weren't the lowest you'll find, but it definitely wasn't busy. We were originally only going to be there for 4 nights, but ended up getting bumped from Vero Beach for 5 nights due to some maintenance issues with only a week's notice, and they extended our stay at Riviera. We were pleasantly surprised at how easy it was to make ADR's last minute or even walk up. We plan on going back again next year at the same time for a week.
The one negative for us, staying at Riviera was the skyliner was down the entire time we were there. They didn't announce the closure until after we'd made our reservations and by then everything was booked (we are DVC) so we just stuck with it. I will say though that with one exception on our last day we never waited more than 10 minutes for a bus the entire trip. I don't know if they prioritized the skliner resorts to keep folks from complaining, or we just got lucky.
Overall it's a great time to go, and we realized that
Festival of the Arts is now our favorite of the Epcot festivals. The food was better than any other in our opinion and we loved seeing all the art work and meeting the artists. Such a fun event!