The EH Holy Grail acts as my practice pedal and backup to my Weber 5G15 reverb unit. I have to say, it is a good alternative to an authentic Fender tube reverb. The sound is a little less trebly than the Fender '63 Reissue Tube Reverbs, which in my opinion is a very good thing. It won't cause you to have to alter you amp settings to eliminate the ice-pick character of the reissues. It also has a very credible tube-reverb sound. There is a narrow band, about 3/4 turns of the reverb depth dial, that marks the sweet spot for classic surf reverb when set to the spring reverb position. The 'Hall' setting is also good. The odd "flurb" setting is virtually useless; it is a cross between reverb and a chorus, or perhaps a flanger, and doesn't really contribute much to the classic surf sound.
This is a viable alternative to true tube/spring reverb boxes, at about one-third the cost. I got my pedal for under $100. E-H makes very sturdy pedals that take up way too much space on the pedal board, but nonetheless do what they are supposed to do. If you are looking for no-fuss tube reverb sound, the EH is a reasonable alternative to an actual tube reverb box. That said, don't expect the full-on spitting reverb sound that you will get from an actual Fender unit. The Holy Grail is close, but no cigar. An unfiltered cigarette, perhaps.