The basic problem here, highlighted by Verdinut, is that with no defined problem, or no defined goal, its really hard to say anything about your purchase. Did you need to upgrade if you didn't have an actual issue with your existing system? You can probably answer that yourself better than I can.
Is an $850 purchase a wise one? Can't really tell much because you haven't really defined anything to base a comment on.
As far as the Marantz 5011 goes, its a solid AVR. Its feature rich. It has as much modern connectivity as you are likely to ever use. Its amplification section is well regarded. The company is also making good products so it has a good reputation for sitting around feeling good about what you bought. If you were starting out on a new home theater, or a new music setup, you could do far worse than the Marantz as a starter AVR. So, the choice is a good box as far as comparison choices might be.
Did you solve a problem with $850 bucks? That's up to you.
Most of the time, just as a piece of advice, forums like AH are a lot more helpful BEFORE you make a purchase. If you put a problem statement to the forum BEFORE a purchase, you'll get a ton of good advice based on your problem statement that can be quite detailed and very helpful. After the fact, its kinda tough to be useful