Well, haters gonna hate, nothing can be done about that.
Personally, having now owned the 4520 for about 2 months, I find it to my liking except for one thing I don't understand.
The majority of sound mode settings are completely not only useless, but ruin the sound. In fact those settings are not compatible with any medium format in use today. I'm talking about all the reverb settings. There are not as many useful sound mode settings on the 4520 as there were on my Onkyo TX705. On the other hand, I usually only use one of 3 or 4 at any given time and the ones I use are there, so I'm not necessarily missing anything, but it just feels like it because I feel Denon should have dropped modes like "Arena", "Concert Hall" etc. a few years back.
As for how "musical" it is. Well, it's an AVR so it's only going to do what it does. Sure, separates would most likely have better processing for 2-channel sound, but at the same time since I can't afford and don't have room for two dedicated systems I have to go with an AVR. To my ears, for music (which is what I do mostly with the occasional movie thrown in), the 4520 is "musical" enough. I don't know what "musical" in reference to amps is supposed to be about outside of pre/pro duties. Separation, staging,etc. has more to do with speakers, speaker placement, and in the case of vinyl playback, cartridges and alignment. There is the case of DACS of course and clean amplification.
Different amps can sound quite a bit different. My 4520 does sound different than my Onkyo. Better? Worse? Neither, just different. I do think to my ears that the 4520 does far better with streaming media and vinyl playback than my Onkyo did. I also think that the 4520 has far far better amplification than my Onkyo did and it is proven just by looking at the build.
All in all I think the 4520 is a fine machine.
On a related note: I had a look at the new replacement for the 4520 via info out of Europe and such. I was a little concerned that it may be quite a bit different and even better, but so far I find it to be almost identical to the 4520 in every way except for the UHD stuff which I don't care about. Layout on inside and the rear and front are exactly the same. To me this is all a good thing.
My only question is whether or not Denon finally decided to get rid of all the outdated reverb sound modes.