Not very good to be honest.
I wouldn't as so harsh as to say 'it sucks' but I really couldn't give you a high mark because the graphics weren't yours and it wasn't animated well. I am a HUGE GTA fan and I feel your collab didn't really do it justice. I thought the sound was well done, but I'm sorry the flash wasn't better.
I'm sorry you've gotton so muh undue abuse from being turd of the week, but you can't report everyone as being abusive. Just because someone doesn't like it. At the end of the day enough people liked it, to survive the portal, so next week when there's a new turd, yours will be forgotton about.
I'd like to hope you make a another flash collab at some point, but take the critisism into advice, after all, if 99 people say they hate something and 1 person says they like it, it's better to listen to the 99.