I picked up the H5900 yesterday at Best Buy and love it so far! It was a hard decision between the new Sony S5200 and this one (I considered last years equivalent models on both the Sony and Samsung but they weren't in stock -- I also considered the LG 540 being my G2 phone is AMAZING). My decision was made when I saw the box of the Samsung with "dual-band wireless" stamped on top. I quickly did some research on the Sony and saw it only supports 2.4 GHz. Weird being the boxes usually tell you NOTHING.
So far it has been an extremely fast player in the menus, loading apps, and loading media from my flash drive. Discs load really fast as well. It is so fast I'm assuming it's dual-core, but can't find that info anywhere. Not in the instructions or Samsung's Web site. I did a live chat with Samsung and they told me it was too new and they didn't have the info, but to watch the Web site in the next few days. Not satisfied with that answer I contacted Samsung through private message on Facebook. The guy told me he sent my question to a product specialist.
The app selection is limited but all the apps I need are there: Vudu, Hulu, and Netflix. All run really smoothly and I've had zero buffering. The Vudu app on my old Samsung only have about 1 out of 3 bars for connectivity. On my new H5900 I get 3 out of 3 bars consistently. So the wireless connection on this player is amazing.
If I understand it correctly there are two separate app sections: one section are Samsung apps (like Hulu, Netflix, Vudu, Pandora, Youtube, etc.) and the other section is the Opera store. Amazon is missing as well as MLBTV and if/when they are added to this player I'm guessing they will fall in section one and be separate from the Opera apps. These two sections are segregated on the player too.
I've always wanted to try screen mirroring before and now I can with this player. I turned Miracast on my G2 phone and was quickly able to mirror my phone's screen to my tv. I noticed hardly any lag and could even play Scribblenauts.
Also, I keep getting a message saying something like, "model information in upgrade file does not match with your player" when trying to do a software update. I'm guessing that is because the player is so new. There are no downloads available on the Samsung Web site yet. It would seem like a better idea if you got a message that says something like "no updates available."
Anyway. I love this player and it is lightning fast!
Edit 4/14/14: I just returned this player because of troubles with the Hulu app not streaming and running sluggishly. Had to make a quick panick decision not knowing if it was a hardware or software problem being it was from Best Buy with their insanely short return policy. Also pressure from my wife being I was only allowed to buy this because our 2010 Samsung player never streamed correctly. Already missing Miracast and the nice controller.