At the moment, for gaming, the PS3 is seriously lacking compared to the Xbox 360, but considering how long both machines have been out, this is to be expected. If you think he'd appreciate watching films on the console, then the PS3, with its built in Blu Ray drive, is a good choice.
If he doesn't already have a 360 then I think the PS3 is a worthwhile purchase - it has about a dozen good quality games available, it just so happens that about 90% of them are also available on the 360. But then, if he doesn't have or want a 360 that isn't going to matter.
I guess you/your brother need to look at what games are available right now, decide if they can keep you going until the AAA titles start coming out, and whether the price of the console is worth what you expect to get out of it.