My old Cactus wireless trigger only had one function. A half press would focus the camera and a full press would take the shot. If you set the camera on continuous shooting, a 3 second hold would initiate as many shots as you wish until you press the release again. Handy, but functionally limited.
The Phottix Cleon II C8 (the C8 designates that it's made for Canon primarily through the cable connecting the camera to the receiver) has a ton of features.
First, it can be used without the transmitter. You are probably thinking, "WHAT? That would make it a wired trigger." That's right! The Phottix can be used as a wired trigger. I find this a very innovative idea.
Second, it has a flash shoe connector built into the receiver. This allows it to be placed on the camera in a very prominent and easy to see spot. The Cactus receiver just dangled off the side of the camera and would turn whichever direction it wanted so you couldn't see if you had a good connection. The Phottix can be turned either forward or backward on the hotshoe so that you can see the LEDs respond to the trigger.
Third, the trigger has 3 settings. The first is just as a shutter release. The second has a 2 second delay which is very handy since changing the delay on the camera takes much longer to set and undo. The last is a continuous setting. All you have to do to initiate continuous is to slide the slider into this position and the camera shoots continuously. Again, very handy in that you don't need to go to the camera to change this setting.
It's quite a nice step up and a very handy improvement in terms of features. There is more product information here:
(I have no relationship with Shasinki.com!)
There's also a very thorough review and comparison of the Phottix Cleon II and the original Phottix Cleon here: