I am currently using one and it is a pretty nice controller. I have 8 fans, (3 on one channel, 5 on another), a FM19 flow meter, and an Alphacool D5 plugged up to it. You can change the channels according to what you would like to power/read from. I personally really like the flow meter mode and being able to see in GPM what my flow is. One possible issue is the inability to precisely set a value, it works in multiples of 4 meaning you have 25 possible values for what you would like to have your stuff run at. If you were going to use the automatic mode with respect to temperatures, I have read nothing but positive comments about its capability to deliver. I have not ran into any other problems as of yet, I have only been using it for about 2-3 months and in manual mode. If I were to give an honest answer regarding value I would say it is a good price for what is being given.
When I bought it, I did not have the money to buy an Aquaero. If you haven't thought checked them out yet, they are definitely worth a look. They are a little expensive but you definitely get what you pay for, and that is a very powerful controller. It can pretty much do anything you can think of, furthermore you are able to set precise values (up to a decimal point iirc) for your stuff to run at. The new Aquaero 6 is a monster and would more than definitely fulfill any control needs.
However, if you are just looking to control fans I think both are a little too much. The reason I went with the CW611 was for the flow meter readout and I am too lazy to get inside my case to turn the knob on my D5 so this was an easy solution that fit the budget.
Then again it is all up to you in the end, if you feel that purchasing either is justifiable then by any means go for it.