Heck loh, a Roland MICROcube would thrash the MG15. Those are the 2 amps I have in the music school I teach... and the microcube is clearly more toneful, more dynamic, more tweakable, just more. However, I'd still play the MG15.
Though, the marshall MG15 and Microstacks are pricey and stuff, they do sound fine. Okay. They are noisy too, got to ground them properly. And they really only have 1 sound. And the cleans just just alright. Reverb sounds tiny.
But they are okay. Tone-wise.