It's missing calls all over the place, it certainly sounds like a good candidate. And read into his post

"No what I am talking about is its basic functionality as a phone. I am not even refering to all N900s in general. I am talking about my N900. It is well and truly the worst phone in the world."

You will see he is talking about his phone, not n900s in general. There's no reason to jump down the guy's throat at all.