The Positive Grid Spark has a lot of unique features. I think how much you enjoy it will depend a lot on what you get out of those features.
There are features that I find useless - Auto Chords and Voice Commands - but maybe someone out there finds them useful. The song streaming is useful, but fiddly, and you can do the same on your phone / tablet. The presets are hit or miss, like most presets are.
Bluetooth streaming to the amp is at once convenient and annoying. It’s cool conceptually, but in practice I don’t want my phone to connect to the amp whenever the amp is on, and manually connecting and disconnecting is not any more convenient than plugging / unplugging an audio cable.
The Smart Jam is a really cool feature, if only it worked as well for me as it did in the ads.
The sound out of the amp itself is fine, but it sounds like a small practice amp because it is a small practice amp. I think my Boss Katana 50W sounds better, and I can take my Katana to a jam with a drummer while the Spark is purely an at-home practice amp.
The USB audio interface is useful if you don’t have one. The Katana has one as well, but I think getting a dedicated interface such as the Scarlett 2i2 is money well spent. I do have to point out the amusing selling point that the Spark comes with a “free copy of PreSonus Studio One Prime.” Studio One is great - I really like it - but Studio One Prime is free, is always free, has always been free. A free copy of free software is… not really a great selling point.
Anyway, my opinion is that the Spark is fine as a small practice amp with some cool features. If I had to pick between the Spark and the Katana, I’d go with the Katana - it sounds better to me, and is far more versatile in terms of being able to jam with a drummer. For recording I’d get a dedicated audio interface such as a Scarlett 2i2 and an amp sim such as ReAmp Studio. For a small travel practice amp, it’s a coin flip between the Spark and Yamaha THR, probably leaning towards the Spark for it’s additional features.