I think it is in a good place for simple bibliometric queries. The fatcat elasticsearch API is open at https://api.fatcat.wiki/fatcat_release/ (behind a proxy to filter "unsafe" requests). That works pretty well for jupyter notebook style experimentation if you are willing to learn the elasticsearch query DSL for aggregations and things.

I don't think the catalog has high enough metadata quality today for use in published research. There are some glaring errors and omissions when you actually starting digging in. On the other hand, almost all bibliographic catalogs seem to have such problems. Fatcat, by being open and having an API, does have the potential to aggregate corrections, fixes, and contributions directly from researchers over time.

A particular missing piece today is that there is no categorization or "discipline" metadata of almost any type. This sort of metadata is more subjective, and the catalog currently carefully only includes factual information. We will likely start collecting metadata at the journal ("container") level and can trickle that down to papers. Aggregating, editing, and curating that metadata in Wikidata first, then importing to Fatcat, might be the best and most sustainable path forward.