If there is a complaint about the extradition process itself, there's nothing he can do about it as those rules are established by the Extradition Treaty. If he were worried about extradition, it would have been smart to locate himself in a non-extraditing country, or better yet, not building a company that facilitated massive-scale piracy. I know that all of MegaUpload traffic wasn't criminal, but I also know that Dotcom certainly wasn't ignorant of what was being trafficked across his servers, in fact he profited from it immensely.
But, this issue is one for the courts, and not just the ones in the US: his arrest was at the behest of Hong Kong, the Netherlands, the UK, the US, Germany and Canada.
He has a long criminal history relating to trafficking credit card numbers, insider trading and embezzlement. It's entirely logical that his arrest was completely warranted given the evidence and his history.
He isn't Kevin Mitnick, that's for sure.