i rented twisted metal on psnow for 4 hours.. i came away seriously impressed with everything other then the pricing which has been discussed to death so wont get into it
impressions:
game took a second to do a connection test which passed. I have 28 down/1.5 up to the house and am wired into my router. after which you have the option to start the game instantly (i did). took about a min or two to get going, after that it was just like running a ps3 game locally
i didnt try online, played about 4 - 5 single player races and everything ran great. no hitching, no visible compression that i could see, no input lag that i could tell. honestly if you gave me the "pepsi challenge" i wouldn't have known that it was streaming, i would have just assumed it was a ps3 game being run locally through an emulator or something.
after a few rounds i quit out as i was really just trying it out of curiosity, theres now a twisted metal shortcut on my ps4s menu so i can hop right into a stream (i guess this goes away after... 3 hours or so from now)
all in all it was a pretty cool feeling playing it, though as i have a ps3 slim that works great and over 50 games i dont see myself using this any time in the near future. cool for people that do not however and really impressed with the performance