That gamefaqs thread just seems to be paragraphs of excuses for why the demo is garbage. The reason why, for example, the sprinting is bad is because of the distances the game expects you to cover. If we were talking about FFXIII areas it might not be as big of an issue. The full game might fix all of the glaring issues that the demo has but there's little point talking about things that don't exist yet when we have an actual thing that can be objectively analysed.
FFXIII is a good game that was unfortunately spoiled by am absurdly long build up, this doesn't even have a good battle system going for it.