I went through a phase when I was addicted to trying and buying different reverbs. Reverb, to me, is one of those effects where each one you use has its own unique character; therefore, I felt it was impossible to have too many reverbs. Eos is one of the select few that I'm still happy to have purchased.
If I had to describe Eos' sound in a word, that word would be dense. Eos isn't understated. It's not for adding a little spaciousness to a sound. Eos is extremely rich and cavernous. Some reverbs need to be coaxed into sounding nice and full, but Eos needs to be tamed. It especially sounds wonderful on trance leads and anything that needs to soar and fill out its space in the mix.
The interface is pretty simple; it's attractive, and there are enough options to explore, but not enough to be overwhelming. And for $50, the price is pretty much right. I don't get as much use out of Eos as I'd like, mostly because the music I produce usually doesn't call for such a powerful reverb, but when I do need it, I'm glad I have Eos around.
I have noticed Eos produces some constant low-level noise even when no sound is feeded into it. With just one instance the noise level seems to average somewhere around -105 dBFS, which of course is completely inaudible. In larger projects, though, with multiple instances, the noise level builds up and can easily mess up dithering and may even come audible at some point. So I recommend using noise gate with Eos.
By the way, I tried stacking 10 instances with big and long reverb settings on one channel and the noise came clearly audible. I bounced and normalized a clip, and I must say the result sounds really creepy. If there are any drone/dark ambient producers out there, you might make use of this noise leakage. ;).