AFAIK it isn't, but it's Google, so there's a 50/50 chance it could be deprecated tomorrow.

I'm dying to jump ship whether or not it's deprecated though, because the web and Android apps are just unbearably shitty.

The web app simply fails to keep up with my typing speed (I can't even imagine how they accomplish this), and the unread counts are usually incorrect.

The Android app doesn't even handle the compose SMS intent, so you can't use it as the default for outgoing messages... this was briefly fixed when they folded Voice into Hangouts, but then broken again 6 months later or so when they decided to roll that back.

Oof, I don't know how I forgot about this one, but attachments. I just got a "text/x-vcard" attachment from someone. Google Voice helpfully displays it as "file type not supported" -- there is no way to download it, view it as text, or do anything other than tell the sender that I'm using a shitty Google product and please copy/paste the info out of it manually and send it to me.

I hope it gets even more popular soon to keep it from getting killed. Even in the valley, very few people I know are aware of Google Voice let alone use it. Google deprecation is always on my mind which causes me to stay away from any new Google products.