Really nice work. And awesome improvement over your first map!
Regarding SaintPeter's concerns try the attached 1600x1200 canvas (best cut something out in the middle to get to your resolution instead of scaling it). I had originally made that for a fog overlay image for large maps (which I still haven't finished...). I'll probably upload that as a mapping template also.
While we are nitpicking, there are two white areas besides the two staircases going off from the large room on the right where you forgot to cut out the white background.
Apart from that the only thing I was wondering is the textures, they look oddly dithered as if you reduced the color depth on them. Was that on purpose? Gives the map a certain feel.
PS: If you feel really really motivated you could indicate different height levels by altering the distance/depth of the drop shadow on higher/lower parts.