First of all, I think that guild leaders should be able to transfer the guild to someone else in case they want to quit or join another guild. Its not as easy as Monster Paradise to level up a guild and I'm sure that the people who are in the guild that contributed so much brawl pts would not want to see it go to waste just because the guild master is unable to play anymore.
Second, I want to be able to search for other players in the game. I have friends that join but I cant find them because there is no search button.
Third, I think that the chat should be more efficient. I mean in guild chat, everyone could probably say like about 1 sentence and we get cut off. We end up taking about 3-4 message to say what we wanted to say.
Fourth, I think in GvG, the matchings should be more fair. My guild got put against a top 5 guild for like 4 times in a row, so it was no doubt that we lost all four time, even with spamming cups and jugs. The difference between our points weren't even close. It was like about 10k to 3k. There is no fairness in that! And to make matters worse. When we FINALLY got a different guild to battle against, we got a higher rank guild than the last.
Last of all, I think there should be a way to trade pirates. For those who are unable to charge, they have almost no way of getting powerful pirates to compete against those who do, which might discourage them to play any further.