My build lot is 48/09, I think (not looking right now). I could always feel the slightly raised buttons. I almost can't tell to look at them except when I notice an almost imperceptible curve shape between keys. I've always been pretty happy with the hardware keyboard, especially after it got a bit broken in and softer with use, and couldn't really figure out what all the complaints were about. Maybe the flat/raised difference is why.
I think if my keys were any flatter, I wouldn't like the keyboard very much and probably wouldn't be able to use it because of my fat, stubby fingers. As it stands, though, I can type with it pretty well without looking right at it, except to find special characters. I like the soft keyboards, too (both portrait and landscape) and I often use them for short stints of typing, but if I plan to write something longer, I always go with the physical keyboard. It is a tad slower for me than the software keyboards, but I don't make nearly as many mistakes and I have the D-pad ready for me to correct mistakes that I find.
-SR-