United, Continental frequent flier merger: What you get

Like many newly married couples, United and Continental have merged all their assets. The latest child of their union: combined frequent flier programs.

So what do you get for being loyal to either or both programs? Will you even notice a difference when Continental OnePass becomes a quaint artifact?

“It's a mixed bag,” said FrequentFlier.com publisher Tim Winship. “It protects the benefits of the higher-level elites, the more profitable consumers, at the expense of some of the perks enjoyed by lower-level elites.”

Here are some of the biggest changes, according to Winship:

Ÿ The new MileagePlus program, to be introduced in early 2012, adds a fourth status level to the previous three. The quartet is Premier 1K, Platinum, Gold and Silver.

Ÿ Continental loyalists, previously spared an expiration date on their miles, must now keep their accounts active over an 18-month period or risk losing their bank.

Ÿ Entry-level elite members, aka Premier Silver in the new regime, will no longer be guaranteed upgrades to Economy-Plus at booking. They'll have to wait until check-in to acquire the premium seats, based on availability.

Ÿ For Premium Silver members, the number of free checked bags goes from one to two. The other status levels can check three free bags.

“People in this category will have to considerably lower their expectations,” said Winship. “This is going to degrade the elite status.”

Ÿ Bonuses will increase on the more expensive tickets. For instance, full-fare coach (Y, B) will earn a 25 percent bonus; discounted business class (Z, P) will receive a 50 percent bonus; and full-fare business (J, C, D) and two-cabin first class (F, A) garners a 75 percent bonus.

For program details: onepassmergerupdates.com/en/op/MileagePlusin2012/ProgramOverview.