Ironically, it's now actually called "Google Chat". I still use it with plenty of people since it allows me to chat via browser, iOS, or Android without any device/brand restrictions.
But in just about every way, it is the same or worse than their previous offerings (the older "Talk" and the later "Hangouts"). They ditched the option to do SMS fallback in the same app instead of improving on integration. Can't just hit the little camera icon in a group chat to instantly start a group video call anymore. Individual and group chats are in separate tabs. Photo and video handling are worse (but at least not downgraded as badly as MMS between Android and iOS).
Honestly I only use it because it sucks to message with iOS users if you can't use iMessage and I/some of my friends don't use Facebook products like FB or Whatsapp.
That might have been Google Buzz? Which automatically followed people it thought you knew. Like automatically linking someone to an abusive spouse they'd run from, and exposing all their chats to them.
