While there's no demand bar like previous version, the airports are still sorted by Large to Small demand. So, normally if you check an airport and see too low demand, then it's very likely that the remaining below airports have even less demand
Until you sort by range, then it is all messed up.
So either you are manually (in your mind as you go through the list) filtering out the ranges, or if you sort by range, you must drill down into the airport details to determine demand.
Why sort by range? Well, aircraft have range limits, so we need to know which airports are within those limits. But not all airports within those limits have enough demand to support said aircraft.
Frankly, if one could filter by demand and range, that would not be a problem. But as it sits today, much more cumbersome than before the UI change, unless you already are familiar with the airports by rote memory or have a database/spreadsheet already developed - definitely not noob friendly.
Couldn't say it much better than GlobalCEO's comments here:http://www.airwaysim.com/forum/index.php/topic,47816.msg266706.html#msg266706
UPDATE: Must apologize, as I see, after joining a new game world and doing Route Planning with the new UI, that there is a filter box on the search for Airport Size. This very much mitigates the problem I mentioned above. However, you can only select one size at a time, and it would be helpful to be able to do a range (e.g. sizes = 4 to 5), depending on what one is looking for.
That said, I still do find the demand bar rather intuitive, even if it may be slightly "confusing" (I bet the ones who complained are all about the fact that the bar was not specific to that route pair, vs just an indicator of overall passenger demand across all routes - seems intuitive to me the latter, but that's just me as a noob).