Bing Travel combines tools that came with Microsoft's acquisition of Farecast with content from MSN Travel.

One of the highlighted features of Bing Travel is Price Predictor, which is supposed to give a "buy now" or "wait" indicator to help people get the best airfares.

The trouble is that Price Predictor is severely restricted and doesn't even work on one of the world's busiest routes (Melbourne-Sydney).

Price Predictor apparently only works for certain cities and for flights within the US or between the US and Europe and the Caribbean. And even there it's restricted to round trips, economy fares, and a certain time horizon.

Excuse me, Mr Bing - it's bing.com, not bing.us!

Another issue is that when you click on a "Book with" link, you may be redirected via a doubleclick.net URL. That happens with orbitz.com links (and possibly others) and presents an unnecessary problem for anyone behind a proxy that's set to block notorious tracking sites.

What else is good and bad about Bing Travel? Please read on.

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Also, if you click on a Virgin Blue booking link, you're merely taken to the airline's home page - the flight details from Bing Travel are ignored and you have to enter them manually.

A particular concern is that there's no transparency about which booking services, airlines and hotels (individual establishments or chains) can be reached through Bing Travel. So it's hard to be confident that you're getting a good price, let alone the best available.

That said, there are things to like about Bing Travel. The interface seems well designed, especially the use of sliders to set acceptable times and the maximum price.

And flights can be filtered by arrival times rather than just take-off, which can be very handy. On business trips, you generally want to arrive by a certain time, so this saves doing the arithmetic.

If there's an airline in the results that you have an aversion to, one click of a checkbox is all it takes to exclude it from the list of fares.

An interesting interface design decision is that if you want to search for a hotel room as well as a flight, the two sets of results open in separate windows. One one hand it reduces clutter, on the other it moves away from the possibility of a single booking (intermediaries such as orbitz.com appear in flight and hotel searches) and presenting a single itinerary.

On the subject of hotel bookings, how hard would it have been to provide a city map showing the location of each hotel in the results list. Then you could centre the map on a point of particular interest (eg, the company you're visiting) and adjust the zoom to describe an acceptable radius, and that could act as an additional search filter.

So Bing Travel's made a good start for US residents, but needs a lot more work before it is useful for an international audience.