The basic concept behind the Swiffer Carpet Flick is to keep your floors clean between vacuuming. In practice, it isn't incredibly effective and requires the frequent replacement of expensive sticky pads.
It's useful, though, to have a sweeper handy which you can use to sweep the floor in a hurry without having to break out the big vacuum and tussle with cords. However, I think that the old electrostatic hokey which we got for free at a garage sale is better at doing that job.
Ultimately, the Swiffer Carpet Flick will not replace your regular vacuum. It's basically good for little dirty jobs which tend to crop up on a daily basis. Often we find that debris has fallen on the floor immediately after we vacuum, and the Swiffer Carpet Flick helps immensely with that type of debris.
If you absolutely can't find an electrostatic hokey/carpet sweeper for a decent price, then the Swiffer Carpet Flick is a good substitute. However the manual hokey should be your first choice.