Lady La-La drops Lady La-La's Singing Shell, a bind on equip item level 292 (equipable at level 80) healer trinket. On my server it sells for a couple hundred gold. She also drops around 20 gold, and for leveling characters I'm sure killing her yields a hefty amount of experience.
Upon engaging her if you have your sound on you will hear music similar to that of the D.I.S.C.O. item from the WoW TCG. She'll debuff you with Briny Romance (frost damage) all the while she'll have up her Siren's Song which causes all nearby enemies to dance. Thankfully upon her death the music stops.
She is also one of eight rare spawns in Vashj'ir. All of them are:
- Ghostcrawler (Spirit Beast Crab) - For lvl 85 BM hunters, can not be killed
- Mobus <The Crushing Tide> - Group Boss, drops a nice epic polearm
- Poseidus (Sea Horse) - Drops Reins of Poseidus, a bind on use underwater mount
- Shok'sharak - Faceless one, drops some booties
- Lady La-La - Drops a nice level 80 healer trinket