This release concentrated to fix all the reported bugs and glitches that were collected by the community over the last years but also many new features have been added.
Some of the outstanding new features might be the Quake Live physics including the cylindric hitbox, a brand new anti-cheat system to catch most of the annoying aim bots and auto-shoot hacks, the advanced callvote configuration giving server admins absolute control over their servers and the frame-rate independent physics to make the game generally more fair, especially to those with less powerful hardware/computer.
Update: Excessive Plus v2.2b is available now.