51 stars won't look bad on the flag. Some arrangements are actually very nice.
This is the traditional one:
http://a.abcnews.com/images/ABC_Univision/reddit_flags_FlagS...
Some more creative takes a la early US flags:
http://a.abcnews.com/images/ABC_Univision/reddit_flags_FlagT...
http://a.abcnews.com/images/ABC_Univision/reddit_flags_flagc...
- People are US citizens, but can't vote in any national US election, except when they literally happen to be in any other state, then they can vote for President and that state's congressional representatives, and that state's local officials.
- The rationale for setting Puerto Rico's as a territory is prettttty racist by today's standards.
Against statehood:
- Federal money going yet somewhere else.
- Diluting representation in Congress.
- 51 though? yuck.