I’ve had one of these almost since they launched them. I did a brief review of it in my Learning Log.
In a nutshell, it’s an OK practice amp, but it’s been massively overhyped and there are other options which may be better, depending on usage and requirements.
Examples are the Yamaha THR10ii (which does many of the same things as the Spark, in a similar form factor and which I think sounds better), and the Boss Katana 50 which, for around the same price, you get something which is a whole lot more than a bedroom practice amp (unlike the Spark, you can use the Katana for rehearsals or even gigging), which gives a lot more versatility of effects, and which sounds a lot better than the Spark.
For what it is, the Spark is a decent-ish practice amp/Bluetooth speaker at it’s price point. But, for me, it’s not at “magical”, nor is it significantly different from a lot of other products out there.
Cheers,
Keith