Canon's DPP vs. Lightroom 4

I have a 5D3. I use Canon's DPP to make minor changes to my raw photos. Forgive my lack of knowledge. I have never used Lightroom or Photoshop. My question is, what would I gain if I buy Lightroom 4? What is the advantage of Lightroom 4 vs. Canon's DPP?

The only alteration I would do to my raw pictures is modifying white balance, brightness or switching to black & white. That is all.

Give me one or two good reasons why I would benefit from using Lightroom 4.

Thank you,
Ali.