my corona chorus emits a squeal when it's switched off and on a crunch/gain channel. though that could also be my ratty old cables since it doesn't have that problem on a clean channel (and since i only use chorus on clean stuff anyway, it's not really a concern and could likely be an isolated incident, but just something worth noting).
that being said, i enjoy it. i've tried many other chorus pedals and found they either had too little or too much oomph and often gave me a more thin, processed sound as opposed to the simple sparkle i was looking for. as others have stated, the corona is nice and subtle and has enough tweakability to fatten up and brighten your tone without overtaking it. i don't have the patience to deal with the toneprint feature, so i basically stick with the chorus and tri-chorus modes which work just fine for me. it's definitely not an 'endgame' pedal, but for its price, features, and sound (for my particular applications), it's definitely the best i've tried compared to its peers, and good enough to stay on the pedalboard until i feel like taking a leap on some $400 boutique crap.