For many the most important part of the update will be the keyboard optimisations. In earlier firmware versions some users have reported that the device can skip key strokes when entering text at a high rate. This appears to no longer be an issue.
Do let us know, in the comment thread, if you notice any other changes.
The easiest way to update the firmware is to use the Device manager application (Application menu -> Ctrl. panel -> Phone -> Device mgr.). Choose 'Check for updates' from the Options menu and follow the instructions.
The E75 will preserve your data and applications when updating to a new firmware, but it is a good idea to do a backup anyway.
As with other Nokia updates the firmware becomes available for different variants (geographic regions and operators) over time. If it is not yet available for your device try again at a later time.
Thanks to @tobypaw for the heads up.