experience with bidonthecity.com

No but minimum bids look pretty high in some cases (some of these units were previously listed at 10 - 20% higher than reserve), so unlikely that they even received offers at the minimum bids. Looks like a bit of a gimmick vs. true auction model to me, just like the minimum bid auctions going on in the hamptons resulting in nearly no sales. Only way to have a worthwhile auction model is no reserve and no one seems to have the balls to try this.

No -- I looked at the terms of the auction (buyer pays 3% broker fee and seller pays 3%, no real opportunity to negotiate contract, high minimum bids, etc.) and the results of past auctions and decided it wasn't much of a deal. The fee is no less than a normal broker, the sales prices aren't lower than a normal broker, and the process of buying is less friendly to the buyer than a normal broker would be. This might be mildly beneficial to a seller (they get the buyer to chip in half the commission, after all) -- but on the buy side it seems like a losing proposition. So:

For a seller in a hot market -- maybe an interesting idea, if they can find buyers who will bid.
For a seller in a slow market -- almost certainly a waste of time.
For a buyer in any market -- I don't see any benefit whatsoever.

There have been some previous discussions on this. You might want to look at those also:

http://streeteasy.com/nyc/talk/search?search=bidonthecity

Zoe