I've tested this with a few prints so far and it is amazing. Takes my bed a little over a minute now to heat up to 100 deg C! Before I had a 12V heat bed that took 20+ minutes to heat up to 100 deg C and could barely hold the temperature. If you have a 12V heat bed currently throw it out and buy this!

* 4 stars for shipping because of a lack of a tracking number but this is just a preference and in no way affects how great the product is. It just meant that I got a surprise at my doorstep after a week or so :)
* Defaulted to 5 stars for communication but there was no need to contact the maker.
* 4 stars for documentation - it is complete and adequate to do the job though it could be a bit more polished

So, I ordered this as sort of a test of Tindie (my first purchase) as well as supporting a Hackaday.io project. Now after running with the product installed on my printer for over a week, I've become forced to write a glowing review. I normally don't take time from my busy life to review things unless they're horrendous or amazing. This is definitely one of the latter.

The things that stand out to me are:
1. Documentation - the writeup on Hackaday.io is detailed and documented well with pictures. The only thing I would change about it is to add a diagram showing how to connect to your 3d printer's controller - but really it isn't any different than your old heated bed. Also, with the SSR chosen, you can do PID just like the old DC heated bed you probably used.
2. Safety - the little things like including a cover for over the SMD LEDs and the thermal fuse, copious heat shrink, in-line fuse, etc. These all add up to a well thought-out product with safety not taking a back seat to convenience or cost.
3. Cost - what you get for what you pay is well worth it. The SSR itself is not cheap and is a good brand. Nothing was sacrificed in the name of making money - rather I'm actually very surprised that this product can sell for what it is and the maker actually feels it is worth his time to produce!
4. Community - on top of it all, I would have bought it to support Hackaday and Tindie and the maker - if for no other reason than to help support another maker and not to support some large corp.

Thank you! I hope you're still selling these when I make my next printer and need another! Consider creating a circular heated bed as well for the delta people out there? That might be my next build.. :-)