25....seconds? What was your f-stop? I shouldn't talk, I got one of those super ND filters recently....
f/22. I have 5 shots pretty similar to this one (albeit with different fireworks) and one that is really blown out. By the way, I welcome constructive criticism to any of my shots--that's why I'm posting. Prior to June, I didn't even know what "DSLR" stood for, so I have a lot of learning to do, and you all seem to pretty well know what you're doing!