i used Cloundflare before. It have many useful and a lot of harmful ( bug )
1/ Useful :
* Save traffic and bandwitdh :YES - you can save a lot of traffic and bw .
* Website Speed Increase : YES
* Firewall, Spamer, DDos , ... : YES , but not sure - i see it no effect
2/ Harmful :
* Sometime with some ones access your site - it display SITE OFFLINE ( actually - your site running and online )
* Your site will down 1 times ( may be 2,3 ) /1 month - sure 100%
* Because when used CloudFlare, you will be given IP with hundreds of other sites, as well as the use of shared hosting
with a public IP that. If unlucky, general IP was blacklist the domain you will also be negatively affected to a certain level.