Hi essentialmusic! This was an interesting mix to critique, because I had an instant negative response to it the moment it started, but that gradually converted into rather a positive response after repeated listening! There were a couple of things I initially reacted against. Firstly it was the mix's overall tonal balance: it's very light below 100Hz; there's a slight muddiness in the 100-300Hz region that affects the bass guitar, solo guitar, and vocal tones; and the 2-4kHz region feels overprominent, not least because there's a rather scratchy 3kHz peak in the vocal sound. If you consider Hannes's crooner-ish manner of vocal delivery, and listen to the vocals in the rough mix and the Ben L'oncle Soul reference, it suggests that Hannes is a fan of warm-sounding vocals. (And I can personally confirm that he is from my experience mixing his album, as I had to revise the vocal sounds in a number of my first-draft mixes on those grounds.) So putting too much high end in his vocal, even in a pop-targeted number like this, is quite a high-risk move.
My second problem with the mix was that the bass, kick, and sidestick/snare all feel rather weak, diffuse, or distant in the balance compared with the rest of the arrangement. Unfortunately, this impression was emphasised psychologically because the first snare/cymbal hit sounds like it's been overly attack-enhanced (by virtue of hitting a buss compressor 'cold', I'm guessing), and that only throws the reticence of the following drums into starker relief. The kick-drum also has the problem for me that it seems to fall between two stools, somehow: it's neither punchy enough to really define the rhythmic groove; nor is it full and sustained enough to be a 'fat kick' statement in its own right. As a result it just feels a bit buttoned-up and polite. The snare, when it arrives, is a little better, but still it doesn't really have the midrange solidity to deliver the fills (such as the one leading into Chorus 2) with a sense of confidence and authority.
However, once I began to get past these initial impressions and my ear naturally began to adapt to the overall mix tonality, I became conscious of lots of more creditable mix characteristics. For a start, I thought that the remainder of your balancing decisions actually felt rather good, when taken in relation to the lead vocal, with a nice range of guitar-tone choices into the bargain. Clearly, having an upfront vocal is a definite advantage as regards the mix brief here, and there is good clarity, with tasteful use of mix effects for blend and space. The stereo width is pleasant, with decent mono-compatibility, and the bass, despite seeming rather aneamic on account of the overall mix tonality, nonetheless translated well to small-speaker listening because of its midrange content. So if you'd just used a bit of master EQ, given the kick and snare more prominence, and rounded off the vocal's upper midrange, I reckon I'd have responded to this mix much more positively straight away. That's the psychological minefield of mixing for you...
Once my general opinions had settled down, I did spot a few little niggles in addition: the Hammond has a rather fatiguing 'whistling' quality to it that gets a bit distracting in Chorus 2; the Mid-section's texture feels a bit hollow, as if it needs more bass/Hammond/piano warmth; the vocal reverb is a bit bright for me, and the way it catches the consonants dates the production a little, I think; the Outro texture gets rather cluttered in the low mids, so you could be a little more judicious in sharing out those frequencies amongst the vocals, whistles, and solo guitar; and automating your effects use would help make the production feel a bit more mainstream -- at the moment, it feels like you've set your ambience for the chorus texture and left it at that, but that then feels rather too loose for the verses, especially on the drums. As a little aside, your choice to pan the whistles and vocals to opposite sides of the stereo picture in the Outro isn't what I'd instinctively have chosen to do, but I think it works rather well, particularly because you've not hard-panned them, so anyone listening on a single ear-bud still gets a hint of what's going on over at the other side.
You've been quite assertive with your arrangement changes, which I have nothing against. The shortened intro has decent pop-centric logic behind it, for instance, as it gets to the lead vocal more quickly, and generally I'm a fan of spreading some of the Outro goodness through the rest of the song as you've done. However, I would query a couple of your arrangement decisions. The main thing is that Verse 3 drop-down. In principle, I can imagine how you might pull off that concept, but it's not quite delivering for me at the moment. It's always hard to define why something like this doesn't work, but the main things that struck me were that I missed the downbeat harmonic-rhythm change at 2:04, and that the return of the bass seemed rather apologetic, which seemed to cast the drop-down more like an accident than a feature, if that makes sense. So I'd maybe experiment further with that drop-down to see if you can make it more immediately convincing.
The second small arrangement quibble I had was the way you've edited the flown-in whistles. I don't mind the idea of truncating them in this way, but I think they have to sound like they were performed that way, whereas at the moment they sound edited. In a production with some EDM influences, this might be no problem (it could very well be a feature to be celebrated, in fact), but here it just feels out of place. Furthermore, the timing of some of those flown-in whistles doesn't feel very well locked into the groove of the song, so I'd try to refine that aspect of the editing too.
Thanks for posting this mix -- it's always fun when I have to wrestle with my own opinions about a mix, and it certainly took me a while to make up my mind on this occasion!