Yes, I used Photoshop... Turned on rulers and pulled horizontal and vertical guides out to check it. Zoomed way in onto the central buildings, especially the Freedom Tower since it's the tallest (and the most important one to be plumb).... I referenced the antenna spire on top of the Freedom Tower, more than the building itself (the building has some slight taper). Viewed at this distance, the antenna spire should be vertical. This made it easy to see what's going on and that the whole image was off level/plumb slightly. In this case the horizontal guide didn't help because the waterfront is too uneven. Verticals are often more reliable anyway. Here's a crop from the original, before I did any straightening, with the vertical guide shown.

Again, it wasn't a lot (less than 1 degree according to Photoshop). But for some reason I have always picked up on anything slightly out of plumb or off level. Both in photos and back when I was in constuction, it just seems to jump out at me when something is off even a little.
And, overall it's a great result from a first attempt.... and 52 individual images is more of a Gigapan image, than a pano!
In this case, I really wouldn't worry too much about other lens distortions... They are minor and sort of shape the image so that your eye is drawn into the center. But they also could be tweaked and corrected with Photoshop, though it would be a fairly big job because you'd likely have to treat differently in different parts of the image. There are also some fairly automatic lens correction profiles... in Lightroom, in Canon DPP, offered by DxO, and others. However, I don't know if those would help here, because this is a pano combining two or more images. To use any ready made lens profiles, it would probably be necessary to correct the individual images first, before stitching them together.
Often when you stitch together an image with any software that does it fairly automatically, you'll find you need to straighten some things and recrop later. This is a pano of three images made with an ultrawide (Tokina 12-24 on a 7D, handheld)...
It required some straightening and cropping... but I didn't try to dial out any distortions or lens curvature (the bushes in the lower corners are actually part of a straight hedge I was shooting over). I was more concerned that someone was walking across the view when I was making the shots and showed up three times in the final composite image. (Cloned two of em out!)