The game library should speak for itself.
Before the PS3, I never really gave a crap about graphics. My game collection was dominated by DOOM and Perfect Dark; I always chose quality over looks.
However, the moment MGS4 began, something inside me came to the surface. The PS3 is stunning in the graphics department. Its games have wowed me in a way the likes of Gears 2 never have; I feel the PS3's visuals are on another level, especially when you're hooked up with a HMDI cable.
The PS3 has a strong title range, and it's going to get stronger. Every new wave of games produces something that makes even the most die-hard graphics whore weep; just check out Wipeout HD!
One of the major questions is "would I buy a PS3 just for Game X"? I bought a PS3 just for MGS4, but then I think most people around here know by now I despise the 360 to a level of hell so deep even Kratos, Leonidas and Doomguy combined can't get to it. However, a much more neutral friend of mine bought a PS3 solely for LittleBigPlanet. He'd have bought it for MGS4, but he realised he could 'borrow' my copy instead... so clearly, there are games on the PS3 that make it worth buying just to play them!