To me they are more trouble than they're worth. The tubes crack too easily and they don't wick all that great, unless you roll your PV around to keep saturating the wicks.
Putting them in a MAP
tank mod makes them far more usable.
Goodprophets.com (out of stock at the moment) sells a tank mod that allows you to simply screw in the internal part of the cartomizer. The tank holds a ton of juice and doesn't "pinch off" the wicks like the clearomizer tubes do. I'm sure the tank mod's rubber will start to effect taste, but when it does I'll just replace the rubber plugs. I've been through about five fills on mine and so far so good.
Cleaning the clearomizers is easy and produces good results. Far better than a regular carto. I've never found a good cleaning method for a regular carto. A cheap $20 dollar ultrasonic cleaner from
Harbor Freight or
Amazon does a miraculous job of cleaning the clearomizers; and attys and eyeglasses, and .... If you don't wait too long (maybe 8mls of juice in between cleanings) they can last a very long time. After you take them out of an ultrasonic cleaner and let them dry, give the clearo three 3 second burns without the outside tube on. This will burn off accumulated residue on the coil. This is known as a dry burn.
At first I wished I'd never bought mine, but after finding the MAP tank mod and using my ultrasonic cleaner they are starting to grow on me. Clearos do have a tendency to leak if you store them horizontally or upside down.
Sorry if this sounded patronizing, but I thought it might help those not familiar with this stuff.