I have almost completed all of the original minecraft textures except the items. I have been using the website http://www.novaskin.me to edit the monster textures and only have the villagers and the end boss to go. What has greatly increased my speed is that I just got a Microsoft Surface Pro tablet/ultrabook. I have been on the lookout for a laptop or tablet that had true digitizer input such as in Wacom technology. The Surface Pro is the first such device to meet all my criteria. And to boot, it’s a full-fledged decently powerful computer. Haven’t tried GIMP on it yet but I’m very optimistic.
One thing should be obvious about my style is that I don’t like the dirty pixel-y look of both Minecraft (by design) and Arena (by necessity). A big focus for me to work within the limitations of the original art to make it more appealing to my artistic sensibilities and create a fresh look. For the monsters/animals in Minecraft, I was particularly trying to make them different. So many texture packs make them all look similar (i.e. a cow is more or less a cow) and to me, it’s not worth doing if it isn’t at least interesting (even if it’s not every ones cup of tea).