I love this fabric, it feels very luxurious. It should be noted this is very distinct from the blended fabric used on some of their other utility shirts. The blended fabric was a little scratchier, warmer, and probably a bit durable. This fabric is so nice though, it is a joy to wear. No undershirt because it feels so nice. I think the cornflower pattern would make a great dress shirt as well.
I also bought the charcoal and love it.
My only gripe is my size is slightly awkward. The small fits me perfectly except the sleeves are a bit short - especially with a small amount of shrinkage after a wash, so I have to go up to the medium where everything else is too big - so need the thing tailored back to basically a small. The small-tall in the dress shirt probably fits me best, but then is way too long for untucked (and doesn't come in the utility patterns)... etc. Tailoring is probably still cheaper than W&P introducing a MTM program though.