Not needing to port numbers since then has been really nice. I'm now on the company cell phone plan and I didn't have to port my number into their plan and put it into their control.
Another advantage is that when my phone got soaked while on vacation I was able to log into my google voice account on my wife's phone and not have any interruption of service.
Here is an article on how to set up an autoresponder with a new google account using google voice and gmail: http://www.zdnet.com/pictures/how-to-build-an-sms-text-auto-...
Google will send you an email for each SMS if you set it up that way. You can have that email be forwarded to your primary gmail account in addition to setting up the autoresponder.