Arduino is fine if you just need some low level / real-ish-time control. I used one as glue for a test setup (converting a voltage input to drive some DC motors via H-bridges) and it was perfect for the job - simple to set up, straightforward to run, a little underpowered (I couldn't quite get to 20+ kHz PWM on the pins in software, so it's a bit noisy) but adequate.

I absolutely agree that an Arduino shouldn't be the core of a consumer electronics device, but for anyone not familiar enough with the field to know that already, it's probably at about the right level.