Panasonic 25mm f/1.7 - very disappointing

I recently received the new 25/1.7 lens and have been using it for about a week and doing a few informal tests.

First, the good points: although plastic, the lens feels robust and nicely balanced. The focusing is very fast and effectively silent. It handles nicely.

However, my copy is slightly less sharp than I expected. Not that it is a bad lens, but it's not of the very high standard than I have come to expect from Panasonic. Also, very puzzlingly, the sharpness does not appear to improve much at all as it is stopped down. It seems pretty much the same at any aperture between f/1.7 and f/8 and only as good as other lenses I have are at f/8 (where diffraction blurring is just starting to be noticeable).

In comparison, the 12-32/3.5-5.6 (an excellent kit lens) is much sharper at 12/3.5 in the centre of the field than the 25/1.7 at any aperture!

One positive point, the sharpness is pretty much the same across the entire field except the very corners - it's more uniform than most lenses of comparable focal length.

I suspect that Panasonic have designed the 25/1.7 as a cheap lens and unfortunately it shows. It doesn't seem to be nearly as good as Panasonic's published MTF charts would suggest. Or perhaps I have got a lemon?