If you don't plan on using the ACS880's in a surround sound/4 speaker setup, then they are great speakers.
I own them and they sound great for a three speaker setup, but as a four speaker/surround they are nearly worthless. The rear speakers are barely audible, and the sound that they do produce is very poor at that.
But, I really have no use for the surround sound effect so I'm not really out much. I only paid $100 for them, so I'm not out too much. They have a remote control and a bigger subwoofer than the ACS48's so I'm happy.