Imogen is great - I think she's incredibly underrated. Each of her albums is very different from the last and always keeps me engaged.
This video is really inspiring and love the message. Was hoping for more Imogen vocals, but this will tide me over until "Sparks" is released.
She's not underrated in any sense of the word. I think the word you may looking for is underexposed. She's got a pretty massive following between her independent work and Frou Frou, but it's not on the scale of say Florence + the Machine.