I'm glad that a watchlist page switch was added so soon.
Me and some other Wikimedia Commons users with high-traffic cats on their watchlist are hoping for a feature that enables separate opt-in/opt-out choices (whitelist/blacklist) for specific categories. Preferably one that does not require copy-pasting or typing every cat name by hand.
Commons deals with entirely different levels of category traffic than the text-based projects, and "power users" typically have massive watchlists with a lot of categories they follow in order to know if someone is making edits that need attention or editing the cat talk.
As things are now, users must choice either unwatching some of our highest-traffic, most central categories, or opt out of the Wikidata watchlist feature entirely.