Short version: I've been producing electronic music since the late 90s and have had experience with audio editing applications. Amadeus Pro is an incredibly competent, fully capable audio editor, with a surprising amount of power "under the hood". As one deepens his or her knowledge of audio editing and Amadeus Pro, it's quite enjoyable to see that this program "stays/grows with you" as you learn.
Consequently, this program has many features that may not readily apparent upon initial use, but are there when you need them, as your learn and as your needs may change.
Less-short version: I've purchased Amadeus Pro several years ago, and without question, the developer provides updates frequently. Thus, even across multiple OSX versions, Amadeus Pro has ben my faithful audio-editng companion.
Like reviewer Gary30 states, learning the control functions take time. At the risk of sounding "lame", however, I nonetheless have to admit that Amadeus Pro "grows with you". That is, this program is usable for those knowing next to nothing regarding audio editing (like me when I first started). Yet, as knowledge grows, I've discovered many feature-rich aspects of Amadeus Pro that address my needs.
Further, I've found the developer to respond quickly to any communication initiated by me, and this program has provided lots of value for me. Yes, there are other audio editors our there that are, by all means outstanding. But, for my money, I'm sticking with Amadeus Pro.
FYI: I am not affiliated with the individual/company that makes Amadeus Pro. I am just a hobbyist producer who values the utility of this program.