American Express Membership Rewards is running a 33% bonus on transfers to Hilton HHonors through January 31.
This means that instead of transfer at a ratio of 1:1.5 you transfer at a ratio of 1:2.
Frankly, you can normally get a 1:2 transfer ratio by transferring American Express points to Virgin Atlantic at 1:1 and from there to Hilton at 1:2. (And for that matter you can do the same with Chase Ultimate Rewards points, making Hilton a stealth transfer partner of Chase.)
It’s even better to make the Hilton transfers when American Express is running a transfer bonus to Virgin. (One ended yesterday.)
Of course, transferring directly to Hilton is faster and involves one less step.
That said, I do not recommend it. I wasn’t even a huge fan of transferring to Hilton before the March 28 devaluation of Hilton points and it makes far less sense to do it now.
Roughly speaking I value a Hilton point at about half a cent apiece, or a little bit less. Transferring at 1:2 means you’re getting in most cases a bit under a penny per point in value.
If you need a small top off of an account to have enough points for the award you want, great, then you’re getting more value at the margin. Boost your balance, spend all of your Hilton points and move on — that’s a great use of this transfer bonus (especially now that the Virgin transfer bonus is not active). But that’s about the only scenario in which I’d be induced to take them up on the offer.