I don't agree with this at all. I've been to Beijing and Shanghai, neither speak nor read Chinese, and I had no problems getting around and seeing things. Beijing in particular is very easy to tour solo. Even in restaurants in Beijing where we were the only Westerners and no one spoke English, we were able to order by pointing at dishes, drinks, etc. I found the Chinese very friendly and accommodating.

As for going to Shanghai, I didn't really care for it. Doesn't seem to have much charm. But then, it's a symbol of the new China, so worth seeing in that regard. Two days is plenty in Shanghai IME. We spent a week in Beijing and still didn't see everything.