I LOVE REHAB! I have both the strawberry ice cream and the gardenia coconut scents, and I use it for deep treatments with heat and for leave-in (mostly in driest parts). I've also used it as a precondish. The stuff rocks~!
Yes, it is worth it.
The only non-protein deep treatment that gets my hair into better condition is the OLIVE YOU by MyHoneyChild which, though I hate the undertone scent, is utterly amazing results-wise.