I don't have one, but have heard from people who do that they work ok. A canister filter is a pretty simple device... a water tight container, a couple of lines to form a siphon and a return, and a pump to help move it along, and some media inside to form a bio filter/mechanical filtration. You get what you pay for however. I have heard that they can be a little noisier than an eheim or other quality canister, and they are a little more flimsy on the hose connections and the latching mechanisms.