It's super easy to use and really slick. You just link a Warcraft Logs parse, and it gives you a genuine breakdown of things you can improve upon.
For example, apparently I double Holy Shock a lot when Divine Purpose procs, causing me to waste Infusion of Light procs. I really should go Holy Shock - Flash of Light - Holy Shock. That was genuinely useful information, provided in an excellent format.
|Suggestions for one of my Desolate Host wipes|
Seriously, this site is an amazing example of web app design!
The only problem is that not all specs are supported. It's mainly healer specs right now. Hopefully it will be able to attract more contributors and support more specs.