It does provide nice options - you can move it where ever you want on your screen or have it show under your cursor (though the default UI has an option for this now). It will highlight the entire frame based on the highest quality item in the loot window (ie, turn the box green if you get a green item). Makes auto-looting quicker by not even attempting to open/close the window. Allows you to link an item (say you find an epic rare world drop) to chat.
XLoot_Group modifies the roll frame and lets you place it anywhere you want. Colors it based on item quality, shows text that tells you whether it's BOE/BOP, and gives you a little info about the item (leather legs). Also lets you link to chat.
XLoot_Master modifies the masterlooter inferface and announces to chat when an item is awarded to a player.
XLoot_Monitor is a separate frame you can place on your screen to keep track of loot that has dropped for you or your party, and you can configure it how you like it.
Is that enough for you?
These are separate modules/downloads.