Anybody Familiar With Google Voice?

I just got my new work cell phone and set it up.  So far, it looks pretty cool (I got the Samsung Galaxy s3)

My goal is that I will stop using my personal cell phone, cancel the line, and save the money.  This will knock off about $22 in expenses per month.  Not a life changer, but a little extra always helps, especially when everything else goes up.

My goal is to keep my current cell phone number.  I’ve heard and read about Google Voice, but I’m wondering if readers can vouch for the service, or tell me anything I miss.

My understanding is that I can port my current number from my current carrier (Sprint) to Google.  They’ll do this for a $20 charge.

I can then assign my new phone issued via work as the destination number for any text messages or telephone calls received on the old number.  They would automatically get forwarded to the new number.

This would mean that I wouldn’t necessarily have to inform anybody that uses my current number of my ‘new’ number.

It would also mean that should I leave my job (and turn in the work cell phone), I will still own my number and can port that back out to another provider should I need to.

Am I thinking everything through? Will this work the way I envision it or am I missing any steps?

Any other Google Voice users out there that can vouch for what I’m proposing or guide me in a way that makes sense?