I have an Onkyo 5.1 system (receiver plus speakers) which is more or less a predecessor to this. So a few points I'd like to make:
1. I bought this thing as a refurb directly from Onkyo ~8 years ago, and it's still going strong.
2. People that complained about the unpowered subwoofer are insane. Mine was on a pillow, which sat on a stool, which sat on another pillow, and I still had my downstairs neighbor come up to complain even when it was on its lowest setting. I ended up removing the bass altogether and just using the other 5 speakers. That was with an unpowered subwoofer, and I can only imagine how powerful a powered one would be.
3. The system is highly reliable. However, there are so many little settings that it can be easy to utterly screw them up by accidentally touching a button on the front, and it may not come out of the box the way you wish. Example: when I first got mine, audio only came out of one set of speakers. Took a couple of phone calls to straighten out, but it came down to the settings.
4. Volume is fine, but somehow the speakers don't actually project all that well. I'm not sure why. Actors learn to project their voices rather than just shouting, and it's a feat these speakers could learn from. That said, I'm not the finicky type who requires some ludicrous sound setup. I have a speaker near my head, and it's good enough for me.
Again, I'm talking about a previous model here. But I must say that I'm overall very pleased with it. Onkyo makes a damn fine system, and I've only regretted a little bit that I got a model which doesn't support HDMI (but the HDMI model at the time was missing a number of other data ports, and I didn't have HDMI anything back then). If it weren't for the fact that my setup works as well as the day I bought it, I'd be tempted to get an upgrade. But I can't justify the cost because of that. Happy to see that some electronics companies still try to make quality products without planned obsolescence.