Depending upon the price. Generally, I look at MSRPs but also factor for retail sales. Figure if anyone has waited close to ten years to buy a console, they can wait a bit more before buying to find the best price.
Of course a strong argument for any previous generation console starts with the used market, both for hardware as well as for the game catalog. You get the benefit of however many years a platform has been available in terms of overall numbers and the benefit of picking up many, if not most of these older titles for next to nothing.
As far as the PS3 itself, it's still a better media player than the PS4 thanks to having greater compatibility with various file formats (CD, various video codecs, music file formats, etc.) and a media remote that actually works as though it were packaged with the console.
Where older platforms don't make as much sense is in buying current games, particularly the cross generation titles unless the whole free online for PS3, PSN+ required for PS4 is a factor. Personally, I have a hard time buying the same game with reduced visuals and performance for the same retail price, or even $10 less.