This mic is the first preamp version of the 451, which was revolutionary in its time!
But despite its technical characteristics (transformerless solid-state preamp, exceptional transients)
Well...
Despite all that it has a well-known defect, the famous dropouts after some time (you need to cut the phantom power, turn it on again and then everything's fine).
The next versions (451 EB, 451B) don't have this defect.

OVERALL OPINION

Exceptional transients.
It's a reference in terms of sound.