I found that Gimp was much easier to figure out.  Additionally, Photoshop does not deal with the problem of the too large canvas size.  Instead you have to crop the image since.  I found Gimp to be much easier to use and for the price of Photoshop compared to Gimp, I see no reason why I would suggest buying Photoshop unless it was part of a packaged deal. 

As for help, I did not need any help from Gimp since I was comfortable with Photoshop, but I doubt this would be true for the average user that has not used Photoshop.  Both Photoshop and Gimp had help files that were useless to me.  I found it was much easier to understand how to do the project in Gimp on my own and, had I not been told how to achieve this in Photoshop, there is no chance I would have figured it out on my own in that program.  I even tried to use Photoshop's help pages and I found nothing helpful.