I have a "Brick" which I used to mic guitar cabs and as a bass DI. I have not tried it on vocals yet, as most of the tunes I have been working on lately with my band have had the vox recorded before I bought the Brick. The vox were recorded using my SafeSound Audio P1, so they are still definitely "keeper" tracks ...but you know how that goes!
Anywho, I have found the brick to add a nice, dare I say it, "warmth" to the guitar cabs I have used it to record, both clean and dirty guitars. It adds a certain subtle "robustness" to the sound, like a scoop of Jamaican Blue mountain coffee adds to a pot of good regular coffee. The Brick has helped my guitar tracks sound as if the amp is sitting next to you and you can feel the harmonic elements of the sound, rather than just the flat "wall of loud guitar" sound my other pre's have gotten me. I can hear more nuances, while also feel more of the power, not just a buzzy fuzzy f#ckfest of distortion.

Clean guitars really cut through mixes much better now, more harmonically pleasent sounding to my ear, less ear fatigue from jangly clean chords. Oh sh1t! I almost forgot, I used it to record a 12-string guitar track!! ...smooth!! Very smooth sounding!!
As a bass DI, I have found it excellent because it translates to tape what the bass "really" sounds like. That's great if you have a good sounding bass, but if not, it sucks, because it is very true to the original tone.
This pre really works into my band's overall "vintage" vibe ....not vintage like 1950's rock, but vintage as in "this is what we really sound like without all the newfangled Otto-Toone mojofication plugins" sound.
That was the long version.
Short version: IMHO you will most likely *not* be disappointed if you buy one!
-mr moon