+1. I seem to have my most enjoyable experiences on these premium routes. These are typically folks who only have to fly a couple times a month and they seem to truly enjoy it.

Yes, there is an overall difference in "service" between the three cabins - that is to be expected. But regardless, you are in a coach cabin for 12+ hours. You will have a fairly good IFE (while not the best in the industry, you will get a good selection of new release movies as well as some good hits from the past). On a triple-7, you are on one of very few carriers who do a 2-5-2 layout so if traveling with someone you can get a good aisle-and-window. Food will be OK. We are not talking 5* restaurant here. But you will be fed. That being said, bring a snack just in case.

Your flight will be fine. Go into it expecting a nice experience and I am fairly certain you will get one.