The art style of original (even pre-expansion) game was already very, very good. Excellent even. Some maps and icons were worse, some were better - as usual. I think I liked the maps in Gods and Kings the most - they were very detailed and pretty accurate, with very well balanced colours and flavour elements like drawings, post stamps, seals, labels etc. Flowers and other very distinct elements appeared in vanilla maps too, like in the Indian and Aztec maps, but this idea was mostly used in Brave New World maps.
I'm glad you like my work, but there's no need to depreciate the work the artists hired by Firaxis have done. They made me enchanted in the game's art style from the day I bought it and played for the first time. Agreed with Wodhann (and thanks for appreciation!) - I try to fit as much as I can into the official style of icons and such. Incidentally, it helped me develop my own style as a painter.
About my tablet: I'm using Wacom Intuos4, A6 size (smallest, so it fits on my desk; or: I couldn't afford a bigger one at the time).