I have one on my truck and Scion, and one going on the next oil change on the Hyundai.
I have had 4 other vehicles with them (Wrangler, Grand Caravan, Elantra and Trailblazer, no idea why I did not take them off when I sold them, I am sure the next owner probably tossed them).
The only con's I see is there could be clearance issues if it is a low vehicle and/or drain plug points downward, and it does drain a little slower than with the plug removed completely (but not that big of a deal for me as a DIY'er, an oil change place would probably hate it).
I know a few have said there could be "sediment" left in the pan since it raises the drain level 1/8" with the threads, but not a concern for me.
Also some are concerned with it getting "knocked" open, which would be very difficult, but they make a latch kit to prevent that if you are really worried about it.