http://www.tesnexus.com/downloads/file.php?id=34245
Introduction:
This mod in his current state (version 0.11) is more a bunch of little fixes and add-ons for Shivering Isles rather than complete overhaul. But even at this state you can notice that the Isles have changed a bit, and these changes may prove themselves quite surprising in some cases. Be ready for finding something that you haven't encountered before!
Most notable changes (be ready to find much more than those):
* Amber and Madness equipments were expanded and fixed; mostly for weaponry, which is now complete and doesn't lack any weapon type found in sets from vanilla Oblivion.
* As above, weaponry of Golden Saints and Dark Seducers was expanded too.
* You can now turn Vitharn Keep into your personal estate, and get there your own smith to forge weapons and armor from Obelisk Shards, found in e.g. bodies of Knights of Order.
* All clothing and armors that were present in vanilla SI but were unavailable (either always or in result of your choices) can be now obtained during the progress in SI's main questline. You can find them in Sheogorath's Palace, among other trophies from your journey.
* All bosses from SI's main questline have turned stronger (including first Gatekeeper, so you may need to get higher levels before being able to even enter the Isles). Now they're more challenging than before.
* Zealots and Heretics will be summoning bound gear now, making them more difficult in combat.
* Aureals and Mazkens will have much better appearance now (no more ugly faces) and their disposition towards you will be updating properly with your progress in SI's main questline.
* After completing the main quest, you will be able to summon portals to take you from and into Shivering Isles (based on Wrye Shivering).
* All areas that were inaccessible during the main quest, after completing it will turn available and free to explore. It includes also Pinnacle Rock and Brellach, strongholds of Aureal and Mazken.
(Complete description in link above.)