They really need to release an official API. I was trying to find out the pricing for API access, but it's not available yet. The API used by this Python package seems to go through an unofficial route.
I guess it's only fair that we may scrape Bard just like Bard scrapes us? I think it's called "disruption" :-)
I went down the cloud console rabbit hole to play with it. Only the bison model was available (of the non-descriptively named gecko, otter, bison, unicorn models). For innocuous prompts I got this error: "The response is blocked because the input or response potentially violates our policies. Try rephrasing the prompt or adjusting the parameter settings. Currently, only English is supported."
Where it did respond, I liked the quality. It was comparable to the GPT-3.5 API. Perhaps a little better even.
MMLU benchmark score agrees with this estimate: GPT-3.5 (70.0%), PaLM 2 (81.2%), GPT-4 (86.4%).
But it looks like you have to rent an instance of Vertex AI to use it. It doesn't seem to be pay per use as OpenAIs model are priced with.
Worked for us.