I liked the previous version, the one with the Verdana font. It's interesting how the current site still incorporates elements of the previous version, for example querying detailed flight status (upgrade lists etc.) still shows the old layout with Verdana font. I think it's a testimony to the old site that anything that requires more in-depth information requires regression to the old layout, as the current layout only seems to allow a dumbed-down display of information.
The current site with the Helvetica Neue font seems to be heavily inspired on dl.com which sports the same font, although I'm not sure if it was UA or DL who first adopted this layout.