Hrm. At first I was going to write that I'd have expected the lady to have somewhat more "lady-like" features (as in, lighter build), but then, the ideals for what's attractive have changed since the, what, Arthurian age? So, thinking about it a little more (and possibly a little too much, this is just a drawing after all, not a philosophical debate), it really works well and suits the period - I think.
Well, in either case, the coloring is nice and balanced, though a bit flat per the standards you've set in the other pieces I've seen. That's not to say it's flat-out-flat, but it seems to lack depth in some areas, especially the wall and - oddly - the grass in the lower right corner, where the lighting suggests the grass is painted on, rather than natural.
I do really like this piece though, just so we're clear.
And, on a bit of a side note, I'd like to share an insight (let's call it "an insight" for the sake of discussion, I realize it's hardly all that brilliant, but my English fails me when trying to phrase it differently) about your work in general - the texturing and coloring are easily your strongest point and in most cases are fairly ingenious. You seem to have an eye (or is "a hand for" how they phrase this?) for placing highlights and shadows in a fairly realistic and suggestive way. What I feel is, maybe, a little less solid is your anatomy (in the pictures, that is; ahem), which looks often just a tad stretched vertically, especially where legs are concerned.
This may be just my perception, this may be intentional stylization, or a number of other things. Still, it's there.
Despite the petty gripes though, I'm pretty much impressed. It's always a cool find when you stumble onto someone with their own style, and the vision (well, that sounds less pretentious in Polish) to execute it well. Kudos.