Some cloudflare cons:
Cloudflare makes websites unavailable if you use services like unblock-us.com (see below)
High amount of 404 I get from cloudflare when browsing /r/pics makes me wonder who is to blame.
Cloudflare is short on locations.
Cloudfront is cheaper if you use SSL.
============
➜ ~ dig cloudflare.com
; <<>> DiG 9.8.3-P1 <<>> cloudflare.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 3675 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION: ;cloudflare.com. IN A
;; Query time: 4847 msec ;; SERVER: 208.122.23.22#53(208.122.23.22) ;; WHEN: Sat Dec 1 18:42:43 2012 ;; MSG SIZE rcvd: 32