+1, especially compared to making changes directly with airlines (Mainland airlines on domestic/regional routes, for sure, and often non-PRC airlines within the region, as well). Basically, if your China Eastern flight gets cancelled or delayed beyond hope, those guys have the ability to put you on a different airline entirely behind the scenes. They already have your money, so they take it and apply it to a new ticket; only on rare occasion, have I been hit with any sort of upcharges or fare differences for this. By contrast, if you were to interact with China Eastern on your own, you'd be looking at either a rebooking on another MU (or FM) flight later in the day or a refund, leaving you to fend for yourself.