The Delta website is pretty basic. It is possible to book fares ok, and the site will list the prices for alternative flights that day (but doesn't check other days). You can now even Select your seat online. however there is very little information on the what else Delta does, the routes, or the planes. There are plenty of "extras" on the right hand side though, with Car Hire and Gift Vouchers, although sadly the "book a lounge" option has gone.
More worrying the main Delta logo changes from page to page, font sizes can be a little wild, and some pages contain pretty much no information at all. However the truly woeful part of the website is the slow loading. On a fast dialup connection it takes about 2 minutes to load just the main page - and it won't allow you to cache any of it. Bad design, and poor performance.