- HTML 5.0 support - which includes offline data storages & access (I got still my security concerns.), video and audio support which makes plug-ins obsolete (sure, it needs the supported format/codecs) and other features
- Privacy Support – it helps to limit the data you leave behind when browsing around; the private browsing mode allows this (no cookies, no history, no caching, no auto-filled stuff)
- Enhanced Search Capabilities – added to the existing URL bar capabilities that are manifold and fast
- Geo-awareness – web apps that need this information can fetch the data from Firefox 3.5 (sure, this needs your okay to do so)
- Many other changes and enhancements that make browsing the web more fu
If you like Firefox, go ahead and upgrade to version 3.5. The new version should be available by the end of the day.