Also, homomorphic encryption isn't about making it more efficient, its about being able to compute any function over the encrypted dataset, and get the same result as if it was over the unencrypted version - this is pretty cool if it works because you could say send over an encrypted version of a program to let someone else test it without giving any details of how it works.

from the paper:

  The purpose of homomorphic encryption is to allow computation on encrypted
  data. Thus data can remain confidential while it is processed, enabling useful
  tasks to be accomplished with data residing in untrusted environments. In a
  world of distributed computation and heterogeneous  networking this is a hugely
  valuable capability.