The 2 synths on the H90 (Hotsawz and Synthonizer) don't track especially great, and anything below a G on the low E string is more often wrong then right (I haven't measured it but latency is noticeable).
All the pitch algorithms are amazing tho and sound great even if some of them aren't really applicable in real life playing. I use an expression pedal and a external aux 3 button switch (i got saturnworks which are great), and mapping the expression pedal to say wet/dry mix is a good way of taming the effect.
Be prepared to spend a good amount of time learning the device and making patches - its really deep and takes time to figure out. The presets are a great way to see what is capable but you will want to create your own patches that work with your playing and music, and that takes time as well. I've been playing with the looper alot lately, and its crazy powerful and taking me days to learn all the options on it..
the H90 is really expensive, but its really well made, has great support (I asked a question on their support forum and it was answered right away), and best of all it sounds great - great sound quality, the algorithms sound amazing, it really feels like you are buying a high end piece of studio gear.
The only way i can think of to make it better is if you could route 4-8 channels of audio over the usb-c to a DAW...