I built my own amp from a Doberman kit and I've always wished it had spring reverb and/or tremolo. That would be a serious amount of work to add at this point, but this pedal has given me exactly what I want (and is probably much better than anything I could have done.)
A pleasant surprise is how well the White Whale v2 works as a preamp. You can overdrive it using the volume knobs, so it's effectively adding two extra gain stages as well. With the amp on edge of breakup the guitar volume goes from clean to roaring overdrive. Love it.
The reverb is trashy and metallic, especially on 3 springs and higher knob settings. It's maybe not for everyone but it can do subtle if you want. It doesn't do the stereotypical long tank "drip", but has its own sound which is more of a clang. Pushing the knobs up gets pretty wild - the controls go to extremes.
This has very quickly become an always-on pedal for me. It's expensive but worth every penny in terms of sound.