Here's a rundown of the changes:
New Look and Feel: We have updated the look and feel of most portions of the website. This includes removing a lot of those annoying pop-up windows in favor of new pages (some are still around), especially in the data upload process. The field edit process also has its own page now, and should feel much less claustrophobic.
New formats supported for file uploads: We now support upload from gpx, xls, xlsx and ods, as well csv files separated by tabs and semicolons. Currently we only support tracks in gpx files, specifically.
Under the hood: There's been a lot of changes under the hood that should make things go smoother in general. This includes a number of bug fixes and interface tweaks.
We know a lot of you have been inquiring about regressions, rest assured we are working on it. Here's a preview of things to come:
(Note that the data being fit in that picture is not literally log base 10 - that's the name of the field)