I'd rather leave this open until some more users report their experiences with CloudFlare.
Specifically, CloudFlare is supposed to eliminate most of the spambot attacks. But I just implemented the mod which determines if a registration attempt is made by a human or bot, via asking several questions. That seems to have stopped the spambots dead.
So, given this mod, I'm wondering if CloudFlare is really worth it. I'd love to hear some opinions on this.
I've been using CloudFlare (CF from now on) for a couple weeks. Personally, I Love it!
Why you ask?

First off, CF is NOT a single program to stop the bad guys. It's a whole suite of programs with servers all over the country (hence the Cloud part). Which by the way, are currently running at over 500 hits per second, only a small fraction of capacity.
Second.. They say "we take the hit so you don't have to" They really do take the bandwidth hit.
Think about all the bandwidth and processor time that is wasted dealing with bots. Every mod we run trying to stop spammers costs us. Be it increased bandwidth (for big sites), slower loading pages, or the time we take to update this mod or the other. You did get that last update didn't you?

Not to mention weeding through logs full of bot data trying to find the important stuff.
Enough of that, you want to know how CF is working for me.
Before CloudFlare, I was running 3 mods, 1 script and had a huge .htaccess file to stop the spammers/hackers.
My SMF error log got so bad I shut error reporting off. (just 1 bot hitting 2 &3 time a second for 2 or 3 minutes makes a log full of junk)
Now I have 1 mod running, Stop Spammer and my htaccess is down to about 8 short lines.

I kept Stop Spammer running because CF relies heavily on the HoneyPot database, which we know only has bots caught by their traps and not reported by humans. Whereas Stop Spammer uses the human data from Stop Forum Spam.
At first I was getting 2 or 3 bots a day sneaking through CF. For the last 3 days there have been 0. This is due in part to the fact that CF also uses human reporting, via our block list.
Noticed a few being blocked that aren't in the Honey Pot database. Good to see! CF is learning.
So far all the features I've tested or tried work very well. Yes there is a bug every now & then, but it IS still in beta. One thing is for sure, they squash the bugs in short order.
One more thing. Ain't done rambling!

I'm wondering if CloudFlare is really worth it.
Let me ask..
Do you like to... waste time, energy, money, bandwidth, and sometimes sleep?
Do you like to.. wade through endless pages of useless data looking for the important stuff?
Do you like to.. worry if that script you just installed has an exploit that a hacker will find before you do?
Do you like to.. make every single potential new member jump through 10 hoops just to join?
Do you like to.. worry someone might post personal info that a bot could grab and use?
Do you like to.. wonder what you would do if your site was hit by a denial of service attack?
I'll stop there...
So... is it worth it?
Just the features the free version will have makes it a no brainier.
Don't get me wrong! CloudFlare isn't the end all be all. But they'll sure make a heck of front line. And it makes the 2nd line soooo much easier to handle.