I used it a couple years ago, and it seemed to work well if you're trying to travel to an expensive/remote location and don't care about what airline you take and what routing you take. You got to choose the dates and cities, and you earned miles on the flights. But chances are, you won't be taking the most convenient route.

I booked a trip from DTW to WAW (Warsaw) that was on UA and LH. But instead of DTW-FRA nonstop, we were on UA DTW-ORD-FRA. Flight from DTW to ORD was supposed to take off around 7 p.m. but was delayed multiple times due to heavy rain in Chicago. Finally, around midnight, the gate agent, flanked by county sheriff's deputies, announced to the already-irate crowd that the flight had been cancelled and that we should show up around 10 a.m. the next day to try again (and that anyone threatening the UA staff would be arrested). Not a great start to a long trip.

Not due to skyauction, per se, just a risk associated with each additional connection on a trip.