Fresh off a recent switch to a revenue-based redeemable-miles earning system, MileagePlus is not nearly as generous of a program as it once was. Reasonable economy and business-class saver fares (kind of) make up for it.
No fuel surcharges
Discounted short-haul awards (for US flights <700 miles)
Extremely limited saver-level inventory
Hard to earn miles in revenue-based mileage-earning system