So the verdict is this little box is a keeper for me. To understand where I'm coming from, it's worthwhile to consider my use case.
I wanted an inexpensive desktop synth with good sound & UI/workflow, decent polyphony, multi-timbrality (at least 2 sounds, this of course has more) and good hands-on tweakability, good FX, preferably with a vintage (and very immediate) feel and sound profile that would work well with the Akai MPC.
I already had the JU-06A which is great, but not multi-timbral. Then there is the Virus which is multi-timbral, but it is not generally vintage sounding, and the feature set is such that it is best used in conjunction with an editor on the computer. I have the P12 desktop but that's in my studio and not going to be a travel box for me, and while it has great delay lines and modulation (build your own fx), I prefer to use it with outboard fx. There's the JP-8080 which is great but large for a travel setup and it is vintage in age at this point, so I wouldn't want to take it on the go, and like the P12 and Virus I like to keep it in the studio for more refined work, while this need was for "idea scratchpad" work.
The "idea scratchpad" is an important reason why I like the SH-4d. In terms of sound quality, as expected, it is not in the same league as my analog gear. When I watch YT videos, I always hear a certain shortcoming (or maybe limitation) of the ZenCore based Roland synths, whether it's the JupiterX/Xm or JunoX or the VSTs... I feel ZenCore in general has a very "in the box" mudiness or lack of fidelity to the sound, which is just the unfortunate tradeoff that one inevitably faces when balancing DSP power with high polyphony and multi-timbrality. The Roland ACB based synths (System-8, JU-06A) are better for overall sound.
All of that said, the SH-4D is a MUCH deeper sound design playground than I expected in a little box like this, and for that reason at the pricepoint I think this is going to be a big seller for Roland. In many ways the depth of experimentation possibilities reminds me of the Hydrasynth. It is not as deep/complex as that, but it does encourage exploration, and it tends to reward the time invested with some very nice sounds.
That last sentence may be key -- what I want to say in parallel there is that this is not a synth where everything is a sweet spot. You have to find the sweet spots to get amazing sounds out of it, and when you do find those sounds (trust me they are not in the presets), you will realize not only what a great value it is but how much fun you just had crafting that sound. And then you realize you were only working on a single part, you have three more synth slots left and a drum track if you want it! That's the real news here.
So, a few caveats....
- Since I bought it as a SONG scratch pad to be used in conjunction with the MPC, I will probably rarely invest the time to get amazing sounds out of it, because my ultimate goal is to just quickly throw down ideas, and if I think the idea is good enough I will export it later (and potentially replace with higher-end hardware sounds). Just the same, the deep sound design capability might be important to some.
- I probably won't use the rhythm track or sequencer at all! So, this review only discusses the unit in the context of the use case I mentioned above. The MPC is the brain of drums and sequencing in my compact setup, so I have no real need for the little button keyboard, the pattern sequencing, and the other niceties. For some, using this as the only music portable making machine available, these could be compelling features.
So for me it fits the bill and is worth the ~$650, but depending on your use case your mileage may vary. I think once more folks realize the depth of sound design capabilities, it's going to be one of those popular underdog synths like the Hydrasynth that reaches a lot of folk's shopping list.