I opened one of these just over a year ago. Great benes, free nights, fairly good point rates if you spend a bunch of time in Marriotts. And yes, they did stop sending me offers once I got the card. They also gave me a ridiculously high limit considering my credit, which I am now regretting, just a little bit, but I'll be okay in a few more months of 'payback' mode.
I haven't read back through the thread so sorry if this is a repeat but I get 3 points (per dollar) for Marriott spend, 2 points for airline, car rental and dining (including fast food and coffee shops) and 1 point for every other dollar spent.
Also has your MR number printed on the card which makes it easy to check and be sure that the FD has your account number on file when you check in.