This is the distinguished black version of the glistening white H90 that has been reviewed a million times. Here are the most important things you should know.
1. The H90 is two complete stereo pedals in one unit. You can use this on two entirely different instruments or chain the two effects on one path (in parallel or series). There are even inserts. I know of no other pedal with configuration this flexible.
2. You get a ridiculous number of algorithms including delay and reverb, modulation, distortion, harmonizer, and resynthesis. Eventide recently added four granular algorithms as a free update. That's amazing aftermarket support! However you do NOT get EVERY sound from their rack mount gear, you do not get amp sims, and certain FX categories are weak (e.g. EQ).
3. You get quick access to six parameters for each algorithm but can dive into all the messy details if you wish, right on the surface of the unit. The nice screen makes it as easy as possible... but it's not easy! The companion software application might be a better avenue.
4. Eventide have created several different interface modes in an attempt to please all audiences. For studio engineers there is a Program Select mode that allows linear scrolling through 99 Programs in each of the four Lists. For musicians there is a Bank Select Mode that groups Programs by three, so that each foot switch selects a Program. Perform Mode allows you to toggle through various parameters. Yes, it's confusing and I can't help but believe there was a better way. Hence the star I deducted.
5. If you want to quickly get sounds for your instrument then this is NOT the unit to buy. If you are on a budget, this is NOT the unit to buy. If you have the time to learn Eventide's system and customise the sounds, then get the H90.
My favourite feature? The LED lights above the foot switches are actually buttons. For use on a desktop these are nicer on my fingers than the clicky switches.
Biggest limitation? If you use the inserts the total latency is 12ms which could be too long. Otherwise it is 4.5ms which should be fine.
Besides more algorithms, what would I like to see? Global LFOs that could be assigned as mod sources to the parameters.