The pun here is definitely multi-layered. This movie suffered from many, many things. Too much action, not enough plot/story/characters. Too over the top. Too much cheese. Too simplistic. Too many villains. Too fast. Too much quick-editing (which is quickly becoming a personal peeve of mine).
Even at its core, it was following Spider-Man 2, in my opinion one of the best comic book sequels (and actually one of the best sequels period) ever done. The first one built the foundation, yet still managed to be good, if only for the thrill of web-slinging around New York (and what kid hasn't wished to do that). The second did everything right -- it focused on the character. What does it matter if you have super human powers, if you can't hold a job, make no money, people hate you, you have no social life, can't land a girl. Top that with an intelligent and sympathetic villain, what's not to like?
The third movie is just plain bad. However, unless you have a huge TV in your home, you may want to still catch it in the theaters -- the quick editing is really bad in this one and its tough to tell what the hell is going on (especially in the first scene). There are no long web-slinging takes... only short brief cuts to disorient the audience and not much else. If you were watching this on a plain TV, you'd probably miss everything.
Unfortunately, the reviews for Pirates 3 is mixed as well. I will still see it on the big screen, because a movie like that must be seen that way (same with Transformers, which looks much like I feared... no expense spared on the cgi and every expense spared on the acting and dialog... I really do hope I'm wrong).