In case anyone is still interested...I've found ptGUI and AutoPano both to be leaps and bounds better than anything else I could find. They are both around 100 euros.
The Canon software is ok for completely standard panoramas (ie exposure doesn't change and horizon runs right across the middle of the images) but if you try to, say, stitch images of a mountain range that is above the horizon, it'll make a curved panorama.
ptGUI offers a lot of manual control and great results if you're prepared to put some time in.
Autopano is ridiculously automated. It even finds the panoramas for you. I've only used it on about 15 panoramas but I've yet to find anything it can't do.
Both ptGUI and Autopano will export photos in layers to PSDs, so you can blend by hand if you want to.
(As a side note, I had no luck at all with Photoshop (CS1) panorama stitching. It made a garbled mess of my images.)