Have it but its collecting dust. Not enough good games out (for the moment)
The analog sticks are the worst EVER they are way to sensitive "loose"(as in no resistance when you try to move them) so when you want to turn just a bit you almost do a 360). Not good at all when for hectical gameplay situations.
The Dpad (actually buttons not pad) is/are great tbh one of the best I have EVER seen (why they fucked up the analogs tho is beyond me) Everytime i play PS3 now I wish it had the Vita dpad (makes me sad...T.T)
The screen (oled version) is great when it comes to most bright colors BUT when displaying darker colors you can see how they used super cheap oled tech. And grey/brown/and black as well as dark blue/purple (all darker colors) are fucked up. (google vita oled spots etc) Playing dark games like GravityRush is no fun that way.
The graphics are great and super crisp as long as the games run in native resolution. Some first party games dont (Gravity Rush etc.)
Using it as a controller for PS3 (maybe PS4) requires you to buy a PSVita "app" for that specific game each time. So its not really cheap.
And as far as I know using it as a WiiU Gamepad type controller requires the game to have that specific option. So you cant just go and play every game on the Vita.
CrossBuy is really awesome. Best thing Sony has come up with in decades.
Everything I said applies to the Oled Vita. I have no idea about the LCD vita.
I think the analogue sticks are the best you can expect from a portable games console.
I don't understand what you mean about controlling the PS3? You can't use it as a controller, but you can remote play every PS4 game, but some developers haven't bothered to impliment the controls properly