Hm, resizing images is pretty much the only thing I do with ImageMagick. I do e.g. mogrify -resize 800x600 * and it just works.
(An aside: sometimes I need to rotate images by just one or two degrees, and ImageMagick sucks at that, at least with JPEGs; it introduces all kinds of artefacts. Imager is much better for that job.)
no subject
(An aside: sometimes I need to rotate images by just one or two degrees, and ImageMagick sucks at that, at least with JPEGs; it introduces all kinds of artefacts. Imager is much better for that job.)