Seeing as how they haven't even announced the beta dates for Xbox platforms yet, and PS4 just had an alpha, of course there is growing discontent from Xbox/Bungie fans.
Who are their most passionate fans? The guys who used to insult Bungie/Halo because they weren't on Playstation or the fans who've been with them for over 14+ years. I understand this though. They're winning over the fans who have never experience their games, never seen the bungie quality, level of polish. Just like many Xbox users have probably never experienced the greatness that is Naughty Dog and their games.
I'm not feeling betrayed though, just a peeved at the exclusivity that now stretches an entire year, exclusive maps etc. A lot of Bungie fans are Halo fans and will stay Halo fans. Unless they can get both consoles, they'll only get one, and especially after the Master Chief Collection announcement, many Halo fans will get an Xbox One and pick up Destiny for that system.
A big danger for Bungie is, their game comes out September. It'll be a hit on the PS4, it'll do well into the holiday. But what comes out in November for Xbox users? Newly remastered copies of the very games bungie made the last decade. So they need to remember this. Is there a Bungie/Halo fan out there that can't wait to try out the new Halo 2 Anniversary? What about a match of Team Slayer on the pit in Halo 3 but this time, with 1080p resolution and 60FPs and dedicated servers.