The plots real weakness lies in the lack of Drifters, the problem in and of itself or rather the potential being wasted is most likely due to the author of Drifters being far too centered on Japan and Japanese history while being less knowledgeable about non-Japanese history which is why characters outside of Japan are lacking to say the least. I would list tons of generals, commanders, kings and so on that I think would have been amazing additions to make Drifters an exciting anime, but the list would simply be too long. Even if we skip all the lesser known generals there are an abundance of famous ones that are simply left out which in my opinion is a complete and utter waste.
Short lift of possible additions; Timur, Genghis Khan, Alexander the great, Julius Caesar, Attila the hun, Qin Shi Huang, Charlemagne, Saladin, Suleiman the magnificent, Wu Qi and Napoleon
Just by seeing these names most people will know the amount of potential wasted by simply leaving them out of the story. Naoshi Kanno was also used, but if you were to use a ww2 pilot that died during ww2 one of the optimal choices would be Otto Kittel which scored a total of 267 aerial victories meaning he's one of the most successful fighter pilots in history compared to Kannos 25. If you absolutely wanted a Japanese fighter pilot that died during ww2 your obvious choice would be Hiromichi Shinohara which sat Japanese records having shot down 11 planes in a single day, author please.
Onto a minor issue is regarding to the portrayal of certain characters and Rasputin is by far the most obvious. If you saw a picture of Rasputin in drifters and you were asked which historical figure it is there's no fucking way anyone would ever guess Rasputin apart from getting it on a wild guess. Surely the Japanese can't hate beards so much to the extent that they're unwilling to create fully bearded characters.
The last matter would be the personality of the characters themselves. Digging deeper into history and figure out what kind of people they truly were and how they acted would have been better in addition to something that would have made it possible for all of them to communicate with each other efficiently. Some lines in foreign languages wouldn't have been a bad thing either if they managed to get the voice actors to actually pronounce foreign languages properly.
Although the story in and of itself is an isekai I also believe it would have been much better without magic. Seeing a contest of raw skill and strategy between famed generals throughout history would have been a much better option. Although the combat still would have been in the realms of fantasy it would have been much better this way.
So in the end the story ends up at a wasted potential/10
The art and sound were both fine, although you can clearly see the similarity to Hellsing as the author is the same, but I don't think the art fits as well with Drifters as it did with Hellsing.
Massively wasted potential/10
