Just checked out the 1.7.1 release of PPSSPP for Windows. The following compatibility problems still exist;
Activision Hits Remixed - Doesn't boot.
After Burner: Black Falcon - Constant annoying audio tone during missions makes game unplayable.
Cars: Race-O-Rama - Screen is obscured so you can't see what you're doing.
Crazy Taxi: Fare Wars - Crashes PPSSPP when you start a game.
Fortix - Crashes PPSSPP after the first level.
Juiced 2: Hot Import Nights - Looks like an overlay on the screen.
MotorStorm: Arctic Edge - Graphics are too bright, flickering black patches under cars, no sound in races.
MX vs ATV: Reflex - Crashes PPSSPP during boot.
MX vs ATV: Untamed - Screen is obscured so you can't see what you're doing.
Pangya Fantasy Golf - Doesn't boot.
Qix++ - Crashes PPSSPP when starting a game.
Resistance Retribution - Graphics are messed up after cutscene ends. At least it doesn't seem to crash at the end of the cutscene now.
Shrek: Smash N Crash Racing - Refuses to load at certain points unless you create a save state and then reload it. Sound is buggy.
SOCOM: US Navy SEALs Tactical Strike - Flickering copy of the game's title is in the middle of the screen all the time. Works properly in 1.2.2.
Speedball 2: Evolution - Doesn't boot.
Xyanide Resurrection - Screen freezes when you start a game and it gets to the end of the level start animation. Worked on a previous version.
Also, it's very minor, but the cars in Colin McRae: Dirt 2 all look too bright. Game plays fine though.
Edit: The music in Flatout: Head-On still doesn't work properly. It keeps starting a nw song every few seconds which is kind of annoying as the box for the song name covers up some of the HUD.
Activision Hits Remixed - Doesn't boot.
After Burner: Black Falcon - Constant annoying audio tone during missions makes game unplayable.
Cars: Race-O-Rama - Screen is obscured so you can't see what you're doing.
Crazy Taxi: Fare Wars - Crashes PPSSPP when you start a game.
Fortix - Crashes PPSSPP after the first level.
Juiced 2: Hot Import Nights - Looks like an overlay on the screen.
MotorStorm: Arctic Edge - Graphics are too bright, flickering black patches under cars, no sound in races.
MX vs ATV: Reflex - Crashes PPSSPP during boot.
MX vs ATV: Untamed - Screen is obscured so you can't see what you're doing.
Pangya Fantasy Golf - Doesn't boot.
Qix++ - Crashes PPSSPP when starting a game.
Resistance Retribution - Graphics are messed up after cutscene ends. At least it doesn't seem to crash at the end of the cutscene now.
Shrek: Smash N Crash Racing - Refuses to load at certain points unless you create a save state and then reload it. Sound is buggy.
SOCOM: US Navy SEALs Tactical Strike - Flickering copy of the game's title is in the middle of the screen all the time. Works properly in 1.2.2.
Speedball 2: Evolution - Doesn't boot.
Xyanide Resurrection - Screen freezes when you start a game and it gets to the end of the level start animation. Worked on a previous version.
Also, it's very minor, but the cars in Colin McRae: Dirt 2 all look too bright. Game plays fine though.
Edit: The music in Flatout: Head-On still doesn't work properly. It keeps starting a nw song every few seconds which is kind of annoying as the box for the song name covers up some of the HUD.