I have been using it lately and I have found that it has enabled me to save some money by not paying the spread. I'm only using it when I'm not in a hurry, it I was any savings would probably be offset by a move in the stock. And also, it looks like IB uses native hidden orders as I cannot see my order on the L2, so it helps not to tip off some HFTs (assuming the exchange is not selling that orderbook, which some might). But I only recently started to play with it so I could be wrong on all of this. What is your experience with it?