What does Google Voice do well? Google voice is one of the oldest web based phone services. I've been using it since it was Grand Central. It's nice to have an alternative way to call people when you don't want to use your personal voice number. It handles most calls, texts and voicemail really well. Plus it allows you to track who is getting your number by knowing who else calls you that you never gave it out to.
What does Google Voice not do well? It can be a bit frustrating as they are often adding new features or changing the service completely from the standpoint of "what is this thing i thought it was that thing". But if you use any google product you know this is not specific to just one product but they do this with all of their products. It could be pivoted and rebranded as a new service tomorrow.
What do you wish you had known about Google Voice before using? That it would change services randomly a few times and feature sets.
Have you used a competitor to Google Voice? If so, how does it compare? no