Quests can be fun. Very light storyline but it's nice.
It does take 3 Orokin Cells and 1 Argon Crystal though.
Sleight of Hand is very situational and for the most part useless.
Eclipse can be useful for solo play, though in a hectic game, it might not make much difference. and having to be in a single light area can get annoying when you have to dodge.
Hall of Mirrors is good. A very nice buff to DPS.
Prism is also great. Tried it in a T3 yesterday with no mods except power efficiency and it cleared a room pretty quickly.
Worth it, get in on the hype.