awkward to clean
The Cyclone feed came along with the tippmann X7 I bought almost two years ago. After putting it through all manner of tests (including quite a few speedball games), here's my review.
The Cyclone feed is notably the only air-assisted loading system around. It needs no batteries. You fire, and the loader is powered by excess air from the firing process. This is, however, one more seal to maintain, and can quickly turn the system into a bit of an air hog.
Though the cyclone can hold its own when used with a semi-auto trigger, its internals can't handle high rates of fire. The stock plastic ratchet (the part that connects the piston pushed by air and the paddles that feed the paintballs) will wear down and eventually break every few thousand rounds, and this process is vastly accelerated if you throw an e-trigger into the mix (like I did). However, upgrading the ratchet to an aluminum version will cause the paddles to lose the give that the plastic ratchet allowed during firing. This will turn your cyclone into a blender.
Should a paintball break in the cyclone, it's pretty awkward to clean thoroughly, requiring the removal of several screws, one of which requires a very small allen key not included with the marker. Failing to clean the cyclone completely will, at best, affect your accuracy; at worst, it'll turn you entire hopper to soup as one ball after another swells after sitting in paint.
The cyclone, in being a large, bulky appendage on the outer portion of the gun, tends to be a large target. Shots that would otherwise go wide might find their mark on the bulky base of the cyclone. This might not be as much of an issue in large, open engagements, but if you're in close quarters, you might want to take this into consideration.
The cyclone feed is an improvement over the basic gravity fed hopper; it maintains an absence of batteries while delivering higher rates of fire. However, the internals are vulnerable to wear and tear, and the expense (and time) required in its upkeep will run as much or more as an electronic hopper.
In conclusion: if you don't have to, don't bother with the cyclone. If you have 150 dollars to spend on a loader (as you will with a fully upgraded cyclone system), you'd be much better advised to go with a rotor or prophecy. I give it a 6/10 for being an improvement over a gravity hopper... but not by much.