The first race in GTA Online is causing an endless 'waiting for other players' freeze right now, and Rockstar are working on it. Running a private session of GTA Online is probably best.
The irony I'm sure isn't lost on that. The servers are having too much trouble for the moment attempting to cope with demand so play GTA Online sorta offline.
Character creation is working but even this part of the process isn't immune to an odd freeze. The two error messages causing the most bother right now are 'Rockstar Cloud Servers Unavailable' and the more troublesome 'Failed to Host a GTA Online Session'. Rockstar warned it would take a while to settle down.
Grand Theft Auto V will apply a title update, where upon GTA Online becomes active.