Ignore the haters NelsonB.
The slowest part of the stock 13" machine is by far going to be the 5400rpm hard drive. You will see the most real-world speed benefits from upgrading to an SSD.
If you are not afraid to get your hands dirty you can save a good amount of money by ordering an SDD yourself and installing it.
I personally am getting a base model 13" pro and then installing the ram upgrade myself as well as installing the optibay mod and having a 128 SSD for the operating system and apps in addition to a 500GB internal drive.