On the Christmas event, while I like the general path forward with this (significant amount of in-game only rewards), I generally dislike a 2 hour window to gain weekly rewards (even if you can catch up during later weeks).
In theory, having a limited time make for a more community feel, but it feels exclusionary. I might be wrong, but just strikes me as odd. Edited: The "catch up" can happen at any time during the week, so my concerns with this are moot.
Black PH is great you can't (directly) pay for more rolls on this (aside from having alts on alts), but I really dislike the release of super rare tradeables. I get it drives player engagement, and likely very beneficial for players getting it, but just doesn't feel good.
Vorkath event is awesome; effectively guaranteed cosmetics, with them being on the drop-table after the fact. Love this; no notes.
On the beta, I really hope there will be functionality in the future ...