I am a musician, and a sound engineer, and this review is coming from someone who works in both careers.
I use two of these speakers for small gigs, of up to 90 people, or as monitors for myself and another on stage for larger gigs. These speakers definitely don't lack power, especially for their size (464 x 292 x 244mm) and weight of 8.5kg.
Sound:
The sound isn't to every musician's taste I don't believe. I would call it flat, but to me, as a sound engineer, that's a good thing. With a small graphic equalizer (I use a behringer xenyx x1222 desk which has one on it) I can get a great sound from these, no matter what venue I play at. As you turn them up they don't lose bass, and the trebles don't distort. I would like to add that the bass sounds as if it is around 65 to 70hz, which may not be low enough for some people, but if that's the case then a subwoofer would be your best choice to buy with it.
Features:
Not many knobs for you to play around with, which to me once again is a good thing. Less knobs means less time setting up, and less things to break.
It has a power switch, a level knob, and a low and high EQ knob. There are two lights, one green to tell you there is power, and a red clip light to tell you that you're going too loud.
This speaker only has a Microphone input, a jack input, and a microphone link output to connect to another speaker. It does not use "speakon" cables, which isn't a problem for me as I prefer using microphone cables, as they tend to be cheaper to buy, can be connected together to make longer cables, and can be used for other equipment (such as microphones and guitar pedals).
Quality:
The cabinet itself seems to be made of a typical hard plastic, and the main speaker is protected with a metal grill. It seems very sturdy, but the one thing I worry about is the knobs located at the back, which are only protected by a bit of plastic from the cabinet that sticks out at the top and bottom. If you're the kind of musician that literally throws everything into the back of the van, I doubt the knobs will last very long.
Conclusion:
I've done a couple of gigs with these so far and they are definitely worth the money. If I had a couple hundred euros more I would have gone for the b212d model instead as it is a lot more powerful, but these are not a bad investment as when the time comes to buy those, the b210d's will work very well as my stage monitors.
Also I would like to add that these are definitely better than the b208d, if only for the fact that the b208d doesn't have a handle. They both produce the same amount of power, but the b210d's do sound a little bassier.