I noticed that the targeted Elite-level 50K RDM bonus for the old 3rd-level MP Signature card that's been all over my view of the united.com website lately has been replaced today by a "60K" promo (50K upfront + 10K based on minimum spend) for the new MP Explorer card. When clicking on these ads, I would be directed to the regular 40K promo page (https://www.theexplorercard.com/MPConsumer40kAFW.aspx) until I had first logged into my MP account, then it would properly display the additional 20K bonus (https://www.theexplorercard.com/MPElite60kAFW.aspx).

In addition to the benefits that have been mentioned earlier on this thread, which basically match the OP Plus card plus early boarding, there are other benefits listed as ongoing promotions at http://www.united.com/page/article/0,6722,1261,00.html. They aren't new for MP Visa cardholders, but IIRC they are better than OP Plus...

These Mileage Plus Choices redemption options mimic the benefit offered by "generic" travel credit cards, which allow you to redeem points to apply toward a ticket purchased on the card. http://www.united.com/choiceshowtoair. This allows you to use miles to defray your cost while still earning EQMs on the flights. The only catch is that you can only redeem miles that were earned from the credit card, not your (larger) general bank of miles.

BTW, if you've never seen the Continental cards in person before, it's pretty cool IMHO. In addition to the subtle background design that is visible in web/print advertising, it features a matte finish--surprisingly feels more premium than the standard glossy cards that just get all scratched up with use. I'm curious if the MP Explorer card will keep the same finish.