The original Phase 90 drove many a song, but Rob Grange used it to make Nugent's "Stranglehold" one of THE phase bass rock and roll tracks. The Phase 45 was the 90's little sibling, with less delay stages. Combining them, and the capability to choose vintage or modern style, into one pedal for the price of a Script Phase 90 is a brilliant gift to musicians.
It's not specifically a bass pedal, but in use, you'd never guess. With highs rolled off at the bass or earlier in the effects chain, the phasing will be much more subtle. But pull the highs back in and the swirl gets deep and glorious. With RS66s on my Thunderbird Vintage Pro, it can make me almost weep with joy.
I'm not a fan of tiny, skinny pedals. My big feet need a bit of room. That and the eye-searing on/off LED (probably useful outdoors) are my only complaint.