I participate in Delta Dining, although I don't try very hard to use participating restaurants. I use maybe one or two each month. Sometimes I use one by accident and am pleasantly surprised when miles show up unexpectedly. I have had almost no problems with miles posting.

You get 10 miles for every dollar spent. If miles are valued at 2 cents each (the usual valuation), then the value is equivalent to a 20% discount. Of course, you get the same amount in cash, not miles. I'm happy to get the miles, but the right choice is not obvious.

Bruce