So, I've had more time to mess with it...
Pros:
1. Their UI is significantly better than the HDHomeRun DVR UI in most cases. And better than most other HTPC user interfaces that I've seen. It's functional, easy to use, and nice to look at.
2. The guide and show metadata is really solid.
Cons:
1. They don't support live TV or watching in-progress recordings (not a huge problem for me, but I hope that feature is coming).
2. The real time transcoding feature (for HDHomeRun Connect tuners) is indeed very experimental. I hope it gets better.
3. Only recent HDHomeRun tuners are supported. Your HDHR3 tuners from 2010 won't work.
Frankly, I'm more excited about this DVR system than I've been for any DVR software I've seen for years!
If you don't want to pay $5/month, why not go for $40/year, or $150/lifetime? If your budget is $0, that's fine, but considering the cost of the rest of the setup (antenna, tuners, HTPC, etc), if someone can make the rest of my setup really shine with fantastic software, I think it's totally worth $40/year or $150.