For me, this immediately discounts it:
> $0.90 per node per hr
That's $648/mo in pure overhead.
I'm not saying there should be no overhead but it shouldn't be that high.
They also optimistically encourage you to try it with a "free" trial. The "free" trial, assuming you haven't used GCP before, gives you $300 credit, which is enough for less than 2 weeks of a single Spanner node.
Plus according to https://cloud.google.com/spanner/docs/instance-configuration, they recommend a minimum of 3 nodes, or $1800/mo.
I know this is targeted at businesses but it'd be nice if we could get smaller "nodes" or something to lower the barrier to entry. You shouldn't have to go straight from nothing to 10k QPS.