I am not going to write a full review as there is no need to re-iterate what others have said - this IS the best chorus pedal being made today.
I haven't tried every single chorus box out here, but I have owned all the following (simultaneously, I might add!) and the Retro-Sonic is my favourite:
Fulltone Choralflange / Boss CE-2 (3 of them), DC-2, DC-3 / Arion SCH-1 (3 of them) / Maxon CS-9 Pro & CS-550 / Diamond Halo / Ross R88 (blue one & black one) / EBS Red Twister / MXR Micro-Chorus / Rolls Twin-Spin / Voodoo Lab Analog Chorus
They have all been eBayed except one of the SCH-1s and the DC-2 (although they may too be heading that way soon!)
The other reason for writing is that I too have done the 'bright' mod as mentioned by 'Slaam!' below except I went one step further (or rather my local tech did) and added a mini-toggle switch to be able to swap between 'normal' and 'bright' mode.
Before this mod my only criticism of the pedal was the slight attenutation of the highs which I felt prevented the vibrato mode from cutting through in a mix (and could make darker-sounding, humbucker-equipped guitars a bit muddy).
The mod is subtle, but it's significant, and I have to agree that it makes the pedal sound even better, especially in vibrato mode. Have no hesitation in doing it, especially if you can fit the toggle switch (which looks cool by the way in between the intensity and level knobs, as though it was there all along).
One other thing - I did experience a fairly loud popping with the true-bypass switch (a common problem) which did not go away, even with the appropriate 'priming' (stomping on it a few times to "discharge the capacitance" or whatever).
Tim e-mailed me a simple way of overcoming this (a quick solder job) and the popping is now gone. The bypassed tone is unaffected.
Reliability/Durability:
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Now the popping is corrected and the 'bright' switch is in I can honestly say my search for the ultimate chorus is over.
If you're reading, Tim, how about making these mods standard?