I timed my 5 on 7.0.4 this morning and it was 2 min and 7 sec...that seems atrociously long for a boot time. My phone is stable when running too; haven't had any crashes into safe mode since JB....
Edit...Found the culprit...Activator. There's an update this morning and in the changelog was "fix boot time on iOS7" Now my phone boots in 40sec