There will always be (known) bugs in Firefox.

You can check out the release notes or monitor (or vote for) the bug reports that interests you.

What kind of bugs are you referring to?

Note that some issues also can be caused by extensions that Ubuntu bundles with its Firefox versions.

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

What is the URL for the release notes?

http://www.mozilla.org/en-US/firefox/22.0/releasenotes/

Just change the version number to see the release notes for earlier versions of Firefox. BTW, Firefox 23 is due to be released later this morning - Tuesday 08-06 ~ noon PST - by Mozilla. Check with Ubuntu support to find out when Ubuntu will release their new version of Firefox 23.

See:

• http://www.mozilla.org/en-US/firefox/releases/
• http://www.mozilla.org/en-US/firefox/22.0/releasenotes/
• http://www.mozilla.org/en-US/firefox/23.0/releasenotes/

For desktop

• latest release
  http://www.mozilla.org/firefox/notes/

• latest beta
  http://www.mozilla.org/firefox/beta/notes/

• latest Aurora
  http://www.mozilla.org/firefox/aurora/notes/

For mobile

• latest release
  http://www.mozilla.org/mobile/notes/

• latest beta
  http://www.mozilla.org/mobile/beta/notes/

• latest Aurora
  http://www.mozilla.org/mobile/aurora/notes/