At times I wonder if people are talking about the same lens. The minor distortion I see wide open is nothing (if you come from most other systems than leica). If you pair it with the compact size (by any standard - and especially for a 1.4) and it's reasonable price, it is actutally a bargain in its own right - even if it is not cheap.
Underrated? I don't know and don't really care. I like the one I have and it is not for sale. When CV discontinues this lens, we will probably see a change to a more positive view of this model - as appears to be the case for all of their discontinued lenses.