Thanks for trying out Firefox Preview! In 5.2, we have lots of new improvements:
New Tabs Tray #11171
Voice search #1216
a11y improvements #9583 #9595 #9545 #9771 #9768 #7752 #7753 #9590
Reader Mode in urlbar #11045
Dynamic bottom toolbar #8775 (removing Nightly flag)
Adds quick contextual menu to tab switcher #10374
Pull-to-refresh gesture to sync history. #2165
Bugs and crash fixes