Man so many answers and not a single helpful one...
So What is PS TV /Vita TV?
It is a PSVita that has neither touch screen/display nor rear touchpad. But has HDMI so you can use it with your HDTV. It is its own device that has its own menu and its own hardware like a Vita. The games run at Vita resolution which is 960 x 544.
It does not ALWAYS come with a controller. you can buy 1 version with and 1 without controller. Why? Because you can use a regular PS3 dualshock with it.
You can either download games from the PSN store or you can insert your Vita game cards into its card slot. It has 1GB of internal storage that is used as a memory card and can be used for small downloadable games. If you want to download Bigger games you need a seperate memory card that goes into the PSTVs memory card slot.
You cannot play any Vita game that focuses on touch controls.
You cannot play most Vita games that do integrate touch controls even tho they are not really needed.
Every single game needs to be patched to run on the PS/Vita TV. (patched by the devs that is) So there is no guarantee to be able to play any new game in the future even if the game completely lacks touch controls.
You can remote play your PS4 games on Vita TV so you dont have to buy a PS4 for your living room and another one for your bedroom but your games will be extremely compressed (since it is supposed to run on a sub HD portable device)
Every 1080p 60fps game will run at 720p30 at max! (and thats not even crystal clear 720p. Think youtube 720p quality)
Remote play has noticeable input lag and if you dont plan on using the ethernet port of both devices (PS4 and Vita/PSTV) you can basically forget that unless you play slow paced games like turn based rpgs etc. Wireless is not recommended at all!
You cannot play any PS2 game unless you pay for the streaming service. Selected PS1 games are available via purchase from the PSN store.
I hope that gives you an Idea what the PSTV is.
When I remember something I didnt mention before I will add it here.
EDIT:
Compariosn between "realtime" PS4 and streamed PSTV. So you can see the imput lag /delay etc. (NOTE THIS IS LAN! WIFI IS EVEN WORSE!)
