Obviously a bottle filler is not dead necessary because you have been using the spigot. So did I. I got a bottling wand to try because it was not too expansive (about $10 in 2012).
A bottling wand makes it much, much easier to fill bottles. Lots. Scads. Oodles. I would suggest a wand if you ever plan to fill more than 6 bottles.
First, it fills faster because the hose and long wand effectively lowers the outlet and creates a pressure head, and the liquid flows faster than directly from the spigot. Second, you can pay attention to the fluid level and not split your attention between holding the bottle just so to avoid splashing, and fiddling with the spigot. I would especially suggest a bottling wand to Mr. Beer users because that little keg flows sloooowly for the last two bottles.
Tip: Some people fill right up to the top and remove the wand to create measured headspace. This leaves about 2 or 3 inches of space in a longneck. My nephew, a professional brewer, stated that is too much space - it wastes the carbonation pressure. You can fill to 1/2 or 1 inch of the top by touching the end of the wand to the inside of the neck.