Hasn’t worked for me, though. The Standard pack I’ve had wouldn’t open, then the game hanged.
Addendum: after relaunching the game, it would appear that the pack has been opened in the end, with some achievement (Sunken City Warrior Collector, I believe) activating from it. What cards I got — no idea.
See also: Reroll Legendaries from Bundle — might be related.
In short, I’d still be cautios about opening these packs right now.