I've used Dynaudio, PMC, Tannoy, Paradigm, misc. other active and passive monitors in the studio and for hifi listening. At one time I thought they were a decent idea -- pre-packaged, simple connections, etc.
But... they are in very many cases significantly more expensive when compared to buying separates -- that is, the same speakers in a passive cabinet with high quality outboard amp and cables.
And there is the sound:
Almost always the active speakers are noisy. And I mean quite noticeable hiss and hum, even with no signal being applied. It smacks of cheap electronics and wiring.
Disperson can sometimes be pretty focused, intended for close inspection rather than spread for imaging.
The sound is what it is. Sometimes there will be removable foam port plugs. Or 'tone adjustments' for treble reduction. These are typically a necessary requirement, for many of the ones I have used have often been 'detailed' in the treble to the point of being hyped, and almost unusable in hifi rooms. And the bass can sometimes be unsuitable when trying to drive them to farfield listening levels rather than nearfield mixing levels. At least for my tastes.
Having separate components allows me to make the tonal adjustments through selection rather than being stuck with the pre-packaged sound.
And I don't like being gouged for high prices for possibly 'questionable' quality of electronics that are hidden in a black box.
Steve