For simple target curve adjustment the 20$ app gets the job done, although with a ****** interface. But yes it's 200$ for the MultEQ-X PC software, which is a bit sad as it's really just a better interface to features that already exist (including interface to some features you cannot otherwise access), but I guess they have a hard time covering development costs otherwise, as Denon probably didn't pay for it. I really think Denon should have, though, considering how many people say Audyssey is crap because of the results they get without the app, when it's really not missing much to get similar capabilities to some of the much more expensive room correction systems.
Audyssey flattens bass by default, which apparently is something that is often undesirable, although how non-flat you want it depends on your room and maybe even personal preference, and that's before taking loudness compensation into account (if you don't use Dynamic EQ when testing and listening).