Apologies, assumed you knew about the new Marshall pedals, the other new ones are an Echo and a Digital Delay.
I've dropped it on the end of my pedal chain, using the Spring setting, low rev time & damping. Like I said, it can be set to give a real OTT reverb, such as a cavernous hall and the like, but for subtle, everything is set low (except the vol/level o' course). I did notice it clashing a bit with my Small Clone when I used that, but that'll just need tweaking (and I don't use the SC that much). Might play around with the placement of the pedal, just thought it'd be better at the end of the chain than anywhere else for now.
I bought a Digi Delay recently to try and "widen" my sound out a bit, but that just sounded too "digital" through the 4104 (well, just too "digital" full stop!), and I was looking at the Holy Grail instead when I noticed these mentioned in Guitarist a while back. Another EHX pedal was not an option as my PSU has 5 9v out's, and I've "adapted" 3 of the power leads to the 3.5mm mini jack connector that EHX use (Small Clone / Small Stone / Vintage RAT), and I had to buy one of those 5 connector leads to get some more "standard" connectors.
It's given the sound a bit more depth which is what I was after.