It's not a bad MMO from what I have played of it, it definitely has a more action-oriented vibe than most others in the genre. Give it a shot. The only downside is it takes forever to download, took me forever anyways, and I don't have a slow connection.
70 bucks is alot of money to add on to an already expensive piece of hardware.
I hope it will work out for you on the 12gig. It should, but you wont be able to add GTA online i think.
Maybe he could search for something smaller, like a cheap 60 or 120 if he doesn't use his PS3 much?
A 12GB PS3 is only halfway usable, I have no clue why Sony would release that. 40GB should be the absolute minimum. Anyway, the GTA V install is a little more than 8GB. You should be able to fit it on there, but it'll be a tight squeeze, and don't expect to play GTA Online until you've picked up a bigger HDD.
12GB is just not enough space, like you said, you could probably get GTAV on there but there is going to be very little room for anything else. Now if @secondheartbeat has an extra hard drive lying around then you could throw that in.