The question is "Is there anything wrong or immoral about homosexuality?" As the title of this blog post states, the answer to this question is incredibly easy. The answer is no. There is nothing wrong or immoral about homosexuality. There is no good argument for the position that homosexuality is wrong or immoral. And, no, because the Bible or Koran says that it is wrong, is not a good argument. And there are plenty of good arguments against that position.
The only reason to accept that a religious text should be an authority on morality is faith that this text is telling us something important. And faith is never a good reason. And most of the people who use religious texts as their justification for their position against homosexuality never follow all the rules that those religious text require them to follow. Their lack of consistency does not impress me, and it shouldn't impress anyone else.
One argument people offer against homosexuality is the argument that it is unnatural. This argument is bad because "unnatural" is not really a coherent term. And even if it were, that means that things like cars and medicine would also be immoral because they are unnatural. And if you say that unnatural means "against god," then we're back to using a religious text or divine revelation to make a claim. That's not rational.
James Rachels' Elements of Moral Philosophy has a really good chapter that takes all the arguments against homosexuality and mercilessly breaks them down and destroys them. He does so in a very clear and concise way, and I highly recommend it.