License. Maturity (is this stable?). Test coverage. Recency of updates (is it actively maintained and up to date?). Size and composition (bug/feature) of is

License. Maturity (is this stable?). Test coverage. Recency of updates (is it actively maintained and up to date?). Size and composition (bug/feature) of issue tracker backlog (how fragile is it? do bugs actually get fixed?). Popularity (if this gets abandoned, will someone else fork and maintain it?). Documentation.