Haven't seen any postings on this, so I thought I'd weigh in. Signed up for the card, and it seems to be a good deal, but only for a limited number of persons. First, we are outside of Philly, which is a USAir hub, so if you want to fly almost anywhere non-stop, you have to use US Air(Ways--what's with that?). Second, the card costs a lot--$125 per year.
For the $125, you get two good benefits (forgetting all the travel insurance, etc). First, you get an annual $99 companion ticket on US Air. Since we use US Air several times a year when we could use the companion, this is a good benefit.
Second, the card gives you 1.2 miles per dollar spent. If you are a mileage addict (sorry MileageAddict--is that trademarked?), and of course put every dollar you can on an affinity card, the extra .2 per dollar can really add up. Since we put all of our personal and my business spending on the US Air card, the extra .2 alone can amount to 1/2 of a free ticket a year. That seems to make it worth the extra $75 dollars over a classic US Air card alone.
Have had it for about three months now, however, and just had to write to them because I have not received my companion ticket yet. Hope that is not indicative of problems in the future.

I have not gotten the Platinum Card, but I must say that I've had problems with the regular card. I have been with AmEx's Membership Rewards for about four years, and then decided to sign up for the NationsBank card when AmEx and USAirways parted ways for a few weeks earlier in 1998 (especially because no supermarket in my area takes AmEx - only Visa, MasterCard, and Discover).
I have never had so much trouble with a credit card ever! In the eight months that I have had the Dividend Miles Visa Card, my payment has arrived late at the payment center once and not at all once and I've been charged a late fee both times. I've never had a late payment ever!
I like the convenience of using the Visa card in those places that don't take the AmEx card, but I'm considering not renewing next year when it is time.

this is a very tricky card on payments. most visa cards give you a 25 day grace period. the nationsbank card is only 20, and it starts when they print the bill. it typically takes over a week to arrive, and they seem to take an unusually long time to process payments. end result: you really have a window of just a few days to get a timely payment in. if you get a late charge, dispute it. they will back off. this is definitely by design. real wiseguys.

Haven't had any of those type of problems with either the new card or with the regular US Air card for 3 or 4 years before that. So, for me the Platinum seems a good bet. I will carefully watch out for the problems you have identified, though.