I just answered this question over on the Large Format forum. I'll cut and paste it here.
I've been using PTgui for about 17 years. Back then stitched panos were pretty new and the few other options available were useless. There are many more options now, in fact pano stitching is built in to most programs like ON1, PS etc. But there is one big difference between them and PTgui. That is that with PTgui you can manually apply control points, it's not normally required but for example if you have a photo with a lot of fuzzy water, or other areas with no real detail, I find that most programs struggle to lock onto what parts of each image should match. PTgui can struggle with this as well, but with it you just go in and create a few control points manually to give it a hand.
PTgui also allows a lot of control over the image placement, rotation of the pano, fixing of panos that point up or down and also format of the output. For example you can output to a layered PSD file where each image is on it's own layer with a mask. Thus if there are some funnies you can get in there and tweak things.
[link to PTgui was here but as a newbie it seems I'm not allowed to post it]
Oh, and the gotcha I mentioned above (in a previous post)? If scanning roll film DON'T include the lettering on the edges. The pano software (all 3 I tried) sees "PORTRA" in one place and two frames away sees another "PORTRA" and thinks that they are matching parts of separate frames, the results are interesting if not that useful

I was tearing my hair out about this and with the other two programs I could do nothing about it as there was no information supplied. Then I looked at the control points automatically produced in PTgui and saw dozens of them clustered around these letters and numbers and realised the problem.
This pic shows a heap of good control points on the rocks but some up on the lettering as well.
This actual example would be OK because they are adjoining frames, I couldn't find an example of a bad match, but you get the idea.
All that said it does seem to be a problem with using RAW files as much as the lettering, so I just convert them to TIFF and either don't shoot the lettering or crop it out before feeding the images into PTgui.
YMMV, but I would give it a try...I just had a look at their site, it costs US$154 these days, yikes. Panos (normal ones) are a big thing with me so I don't mind spending a few $, but that's a lot. Still, it's cheaper than buying a scanner