The bid-ask spread will shrink as (if) the currency stabilizes, and you won't need to round-trip as (if) the currency becomes more widespread. It's not really any different in these respects than any other currency - if, say, I decided I wanted to pay someone in Baht or Rubles or something, it's just that there is not presently much of a market dealing primarily in bitcoin.

I'm not going to push any notion that bitcoin has no issues, and these are issues in the short term, but these particular issues - cost especially - aren't anything like insurmountable.