Simon - I like the colors, so I'll leave those comments for others to make. The stitching looks good, however it's a bit difficult to critique at this size. I understand that large image dimensions are difficult for online viewing, though.
In general, I never use 12mm for panoramas, especially on the 12-60mm. The reason is that there's so much curvature and distortion at 12mm that 1) it makes stitching difficult, and 2) it makes blending the exposures more difficult as well.
I almost always use 25mm as a standard for stitching panoramas, but each to his own. I would have really liked to see a bit lower on this panorama as well. I believe you mentioned this is a 4x1 pano (4 images in 1 row). I would really liked to have seen a 4x2 pano (2 rows of 4 images each), to give a better perspective.
For a first time pano, I think it's great and works really well. Here's a few tips to help speed up the stitching and blending (even if you're using automated software):
1) Use longer focal lengths if possible - this reduces distortion and makes rendering the pano much easier and faster, not to mention with better per-pixel image quality
2) Stop down whichever lense you use to about f/5.6-f/8.0. This reduces vignetting (which is most prevalent on every lense when wide open), which increases the quality of blending the exposures.
3) If you don't have a pano-head and tripod, don't bother with a ball head. I get equivalent or better stitches without using a ball-head tripod than with.
Great pano!
Pictures were taken in the french part of switzerland during a short walk in the alps. Pictures were taken with the E-510 and 12-60mm at 12mm and a polarizer.
--
Tim
'I haven't been everywhere, but it's on my list.'
E3/7-14/12-60/150/50-200/25/25/EC-14
http://www.flickr.com/photos/timskis6/ 
