Here's the list of (subjectively) important changes from v0.3.2.

Enhancements

Use a deduced base branch from remote HEADs, rather than hard-coded default base branches. #127 #145
The change will make git-trim to gracefully adapt to default branch renaming. It might break multi-base branching scheme such as git-flow as noted in the PR. git-flow users should set git config trim.bases develop,master.
Preserve worktree branches #130
Associate local and upstream/remote branches to prevent dangling states #140, #144
Classify non-tracking local branches and non-upstream remote-tracking branches too #147, #163
Print shorthand name instead of verbose refname #106 #108
Print detailed messages why branches are filtered #162

Breaking changes