Whatever you can say against Wal Mart can be said with equal justification against other local players like Reliance. Those who are against Wal Mart are anti-American in their thinking and they only pay lip service to the interests of local farmers and traders.
There will be huge job losses in the unorganised sector when big retail chains start operating in India. That kind of massive shift in employment has to be anticipated and provided for.
You cannot stop or stall centralised sourcing of products in bulk, for a long time.
Those who are against large retail chains were also against computerization in banking a while ago. Technology can only be stalled for a while. It cannot be stopped. Wisdom consists in dealing with the after-effects of technological change and not in blindly opposing it.