I've been using op25 on a raspberry pi with a $20 USB SDR dongle. Less than $50 worth of parts I had sitting around anyway. It works far better than any scanner I've seen so far (as far as decoding goes). Just an alternative to those who don't want to fork out the $$ and have even moderate linux skills. It's not "plug-and-play", but it's not rocket science either. IMHO, it's harder to program a scanner.
Just my $.02