It might be a little cheaper to get the new one, depending on how much, if any, Sony raises the price of the revised PS4 with more storage. The new one will have a 1TB HDD (or at least there will be a 1TB option), but it’s already very easy to replace the current model's 500GB drive with a 1TB drive. That upgrade will add about $60 to the cost of the console, so a current PS4 upgraded to a 1TB HDD will cost you ~$460.
Aside from the much needed additional storage, the new version of the PS4 will use slightly less power, with the power supply changing from 250W to 230W, and be slightly lighter, for what that's worth.
What I’d really love to see is longer controller life, and the ability to easily add an external HDD.