I really want to like Alarm Clock Pro, but it simply doesn't work about 40% of the time. Doesn't wake from sleep, doesn't set off the alarm. It's really weird - I've tried different versions, reinstalling, upgrading OS, running utilities, deleting prefs, repairing permissions, etc.
ACP has a lot of bells and whistles, but if it's not reliable at it's core function, it has questionable value in my opinion.
I recommend PowerController as an alternative. I just discovered it, and so far it's working reliably and is much simpler. No need to enter an administrator password every time you want to set the alarm (the hoops ACP makes you jump thru get really old).