I have been using AMEX the Platinum since October and will share my experience. My sis is a supplementary card holder.

Concierge Service
I have used them to book my stay in Perth. They gave me good rates for Intercontinental. 300AUD per night for the Executive twin. I think it is the same as rack rates so the only  advantage was I obtain a 100AUD dining voucher and late checkout until 4pm. A good choice only for 5 star hotels.

Priority Pass
A good card. I used it and brought in a guest for 3 of my trips aboard. As I also have MBB2Reserve I also used those cards for my other family members to enter the lounge

Treatpoints and MR
Since I can collect both points so far I have collected about 1.5 million points. I intend to redeem 2 business class tickets to NY using Krisflyer miles. Based on my calculation I would need to collect about 2.2 million points. Places that I use to collect points regularly: Tesco, Aeon, Jaya Grocer, Parkson. When I dine out with friends and we go dutch I will usually use my cards and they pay me cash. For places that don't accept AMEX I use my MBB  Infinite Visa which also get 5x TP for retail purchases.

Other rewards
I find the hotel dining discounts useful. At One World Hotel I was able to get 20% off when dining with clients and when I spent RM800 on a meal with my friend at Shang Palace I got 50% off

IMO this is a good card if you travel and dine out a lot.