Cliché Storm: There's an eclipse, an apocalyptic showdown, ancient sealed powers, an ordinary high school student, a Chosen One prophecy, and a tragically dead parent figure. But eclipse, ordinary high school student, and prophecy aside, this isn't the fault of the adaptation; just about all of the rest is present in the original anime and manga. Then again, the anime didn't attempt to squeeze "all of the rest" in at once.
Germans Love David Hasselhoff: Naturally, it did well in Asia (outside of Japan where it lost to Yatterman), going number one early on before dropping off. It should be noted that it was number one for several weeks at Asian box offices, and while the reception was mixed it is still rather popular and well-liked outside the US.
Ham and Cheese: James Marsters as Piccolo and Chow Yun-Fat as Roshi were awesome casting choices.
Narm: The line "The first rule is... there are no rules." is absolutely laughable for some because it didn't convey any sense on what is said.
The bullies' insult of choice: Geeko.
Never Live It Down: The movie itself earned a reputation by Dragon Ball fans and generally, the anime and manga fandom as a terrible Hollywood live-action adaption of a very popular anime franchise. Because of this, the fandom would remain skeptic on Hollywood's attempt on adapting manga and anime into the big screen. The reception of Edge of Tomorrow might have changed this view but perhaps not enough.
The writer, Ben Ramsey, finally admitted in an open letter to Dragon Ball fans that it is an Old Shame of his. So much so that what little of a film career he had was utterly destroyed by the work (as his IMDB page demonstrates).
Snark Bait: Fans of Dragon Ball just love trashing this movie. Just mentioning the film in a Dragon Ball forum post is bound to start a flame war. Even the people who worked on the English dubs of the Dragon Ball anime love to make fun of this movie at fan conventions.
So Bad, It's Good: Most of the reactions were negative, even from those who never saw the animated series. That said, it can be enjoyable. A small minority think it was a decent film in its own right, to the point it could be considered an okay film had it not had the Dragon Ball name. And as stated above, alot of people in Asia love the film.
See what Goku's head collided with when grandpa Gohan knocked him off. Sure, he was falling pretty fast, but melons shouldn't be THAT soft, should they? Also in the previous scene, one of Goku's kicks didn't even touch his granpda. Force Kick in effect? The 2 consecutive failures can be seen in one video.
In Goku's case, in the series, he was known for having a rather hard head.
There's also that one scene with Goku and Piccolo in a Ki blast struggle... that ends with Goku shooting himself towards Piccolo with no propulsion whatsoever and in the same Kamehameha firing pose.
There's also a bad case of Styrofoam Rocks towards the end of the movie. You'll know it when you see it.
And let's not get started with either the obviously fake ape suit substituting for Oozaru or the wretched CG used throughout.
They Just Didn't Care: Though, at least one person cared. According to the script-writer, his original script was a much more faithful adaptation of the original, complete with Pilaf and his gang, Oolong, Pu'ar, the Nimbus, etc. Unfortunately, the script was changed a lot once it was out of his hands. To the point where he felt the need to issue the above-linked apology for the final product.
It turns out this probably isn't true at all - Ramsey admitted in a 2016 apology letter to have gone into the film "as a businessman" and "not a fan" of Dragon Ball (whether this means he was a fan and just didn't care, or he was not a fan, period, isn't entirely clear). There are also conflicting sources which mention that Wong, the film's director, made several changes to the script which actually made it more like the comic, meaning the original script was even less like DB than the final product, if that's even possible.