It just allows you to be more 'spontaneous'. Whereas for Viagra you have to wait about an hour for the effect to take place, this stuff brings it down to 30 mins, sometimes 15 for a lazy lob. It's almost like a redelivered Viagra, quicker to work, lasts as long, whereas Cialis has a longer lasting potency period, think 12 hours rather than 4 for Viagra.
It can be affected by a large meal though, like any ED drug. Oh and keep off the booze too