I have not used that particular pecan picker, but I've used a similarly designed smaller version (about half that size) that you propelled by hand and that worked the same way. They'll work just fine on a nice smooth clean flat surface (who has that under their pecan trees?), but otherwise are more trouble than they're worth. I was very glad I didn't spend any money on one; a neighbor had bought it, found it to be more trouble than it was worth, so I tried it awhile and agreed.
If you have hard, solid ground under your trees, either bare dirt or grass scalped as close as possible, then it'll work, but it'll also pick up as much trash, twigs, leaves, sticks, etc. as pecans.