Maxthon 7.5.2.6400 Beta appears to be a beta browser release intended for testing new features, improvements, and bug fixes before a stable version. Beta releases can be useful for users who want to try newer functionality early, but they may also contain unresolved bugs or compatibility issues.
For anyone considering a beta browser, it is a good idea to check the official release notes for supported platforms, changes, known issues, and security updates. Users who rely on their browser for important work may prefer the stable release until the beta has been fully tested.