Have now tested all my Vita games, with the exception of Ragnarok Odyssey (have it digitally but it's been deleted since I have Ace) and Resistance (also deleted...does anyone even care anyway?)
Sly Cooper also got a patch and now works. Like Killzone and the Koei musou games, you get new control schemes that take full advantage of the PS3/PS4 controller, so it's just like playing the PS3 version.
Despite that tweet posted earlier from James Mielke, Lumines currently does not work. Was also surprised to find that Ninja Gaiden Sigma 2 did not work. That's the only Koei game I tried that did not. Persona 4 looks kind of ugly blown-up. I guess it's expected since it's a PS2 game. And I tried one PS1 game, Dino Crisis 2. Looked hideous, LOL.
Here is my updated list:
Supported:
-Killzone Mercenary
-Sly Cooper Thieves In Time
-Akiba's Trip
-One Piece Kaizoku Musou 2
-Dynasty Warriors 8 Xtreme Legends CE
-Shin Gundam Musou (J)
-Sengoku Musou 4 (J)
-Deception IV
-Senran Kagura Shinovi Versus (J)
-Dekamori Senran Kagura (J)
-Dragon's Crown
-Chou Jigen Action Neptunia U (J)
-Bullet Girls (J)
-Ultimate Marvel Vs. Capcom 3
-J-Stars Victory VS (J)
-Blazblue Chrono Phantasma
-Arcana Heart 3 Love Max!!!!! (J)
-Dead Or Alive 5 Plus
-Divekick
-Sonic Transformed
-Toukiden
-Muramasa Rebirth
-Ragnarok Odyssey Ace
-Magical Beat
-Spelunky
-TxK
-Jet Set Radio
-Musou Orochi 2 Ultimate (J)
-Retro City Rampage
-Ninja Gaiden Sigma Plus
-Soul Sacrifice Delta
-Final Fantasy X-2 HD
-Rogue Legacy
-Pix The Cat
-Malicious Rebirth
-Persona 4 The Golden
-Persona 3 Portable (PSP)
-ClaDun (PSP)
Not supported:
-Ninja Gaiden Sigma Plus 2
-Unit 13
-Borderlands 2
-Hotline Miami
-Phantom Breaker Battle Grounds
-Street Fighter X Tekken
-Rayman Legends
-Ridge Racer
-Hyper Dimension Neptunia Re;Birth 1
-Hot Shots Golf World Invitational
-Virtua Tennis 4
-Hatsune Miku Project Diva f
-Guacamelee
-Shinobido 2
-Uncharted Golden Abyss
-Metal Gear Solid HD Collection
-Mortal Kombat
-Injustice
-Gravity Rush
-ACIII Liberation
-Wipeout 2048
-Olli Olli
-Lumines Electronic Symphony
-Castlevania The Dracula X Chronicles (PSP)
-Metal Gear Solid Peace Walker (PSP)