To be honest the whole thing was just terrible (your mileage may very). But I liked it and it gave me a good laugh.
-Plagiarism (who cares)
-Inconsistencies in the story (For example, there were seven who entered guild, only three made it, but only three died in the description, Haiyang's name changing to Hayang, and Tianishi changing to Tianshi, etc)
-I'm not sure if Tianshi/Tianishi is a legitimate Chinese name, but if not, you could have at least came up with something that did not sound so obviously similar to Tenshi?
-Grammar (who cares)
-It was rushed (just like the show lol)
-Some of the parts would probably be a mind screw for someone who didn't watch Angel Beats (who cares)
Were you caught plagiarizing on the assignment though?