So I hunted this down after hearing it was a crossover between One Piece and Dragonball, because who wouldn't want to read something like that? You have two wonderful artists combining their already loved characters together in what should be an awesome story, right?
The story is completely and totally random, and had I not read One Piece or Dragonball I would have been at a total loss. It makes slight references to minor plot points of the other two stories, but it does not have the "pirates" or "z-fighters" themes at all. It's just these really random characters going around doing their (what we can assume) daily routines. It's totally plotless.
The art is wonderful. It's well drawn, the characters fit together seamlessly, and there's a lot of action in the background. Very common of the OP and DB series. In fact, the art is probably the best thing about this manga, because you can see (with official art!) what the characters look like together.
The characters, again, are wonderful. However, they are also using the same personalities from their mother series, so if you haven't read OP or DB before you would be at a total loss as to what is happening, or why they are doing certain things within the manga.
Enjoyment value was okay; again, it's OP and DB, and even if it is a totally crack story, it was amusing to see some characters together. Props out to Sanji and Roshi hanging out together. That was awesome.
Overall, if you have read Dragonball and One Piece, you should probably read Cross Epoch just to say you did. It's not a great story, but it's still fun to look at the art and see what characters Toriyama and Oda decided should work together, based on their personalities and/or gender. It's not any sort of monumental story that you'll dig out a great plot from, but I would say that it is worth reading.