I've been using GV for over a decade. It's the last Google service that I still use regularly. I use mailinabox for my email/contacts/calendar/drive. I've looked, and there aren't any drop-in substitutes for GV. I've had a Number Barn account with two phone numbers for a few years. They seem to provide better voice quality than most alternatives, but their SMS integration is poor. I'm not sure if they even do voicemail, but I don't think they do.
Looks interesting. I got as far as where it asked me to pay them $15, which I'm reluctant to do without first trying out the service. How does one receive a Referral code?
I've been liking it so far, no issues to report. However, I've only been using it for two months now.
Also, similar to Google Voice, some businesses won't let you use a VOIP number for your phone number.