I've built it & have been enjoying it for a couple of years now. The output is quite sufficient for home use, & the sound is clean, controlled & very musical.
Even tracks with complex bass parts (viz., Jamiroquai, Level 42, etc.) sound detailed & defined. Bass guitars & kick drums aren't "lost in the mud" anymore.
I used an off-the-shelf amplifier instead of the one included in the Roaring Subwoofer plans, only to save time & effort.
It was definitely a worthwhile project in my opinion.