For some kinds of fishing, such as casting in shallow water, sonar won't be much help. For other kinds of fishing, such as jigging, trolling, and downrigger trolling in deeper water, sonar is invaluable. I find color sonar very helpful, as the color provides a lot of information which you don't get from a black-and-white screen. For example, color can help you distinguish between a rock, a clump of weeds, and a fish sitting on the bottom. If you're fishing away from shore at all, GPS can be extremely helpful, as it allows you to go back to structure or to places where you have found fish, provides your trolling speed, and can help you navigate. I haven't been very impressed with down imaging sonar, which hasn't been useful for the kinds of fishing which I do, but for fishing in shallow water with a lot of weeds, logs, and other such obstructions it might be more helpful. I'd like to try sidescan sonar, but a major disadvantage of sidescan sonar on a kayak is that the transducer has to be mounted below the level of the keel of your kayak, which pretty much means you have to mount it on a boom next to your kayak.
In general, if you like to do kinds of fishing where sonar and GPS will be helpful, I suggest that you not go too cheap. You'll probably be unhappy with a bottom-of-the-line fish finder, and when you finally upgrade to a better fish finder, you'll wish you had done so years earlier. I suggest you consider buying a fish finder in the medium price range which has sonar, GPS features, and a color screen.
I have a 2014 Revolution, and the transducer pocket is great. It completely protects the transducer without degrading the performance of your fish finder. The kayak comes with a bracket for Lowrance transducers, but if you buy a fish finder made by another manufacturer, for a couple of bucks you can get brackets for transducers made by other manufacturers. A minor issue to be aware of: if you land in sand or mud, the sand or mud can pile up on the cover of the transducer pocket and interfere with the performance of the fish finder, so wash out the transducer pocket periodically. A sidescan sonar transducer won't work in the transducer pocket.
Mount the fish finder unit where you can reach it easily. If you mount it in front of your feet, or someplace else where it's awkward to push the buttons, you won't end up using the features of the fish finder as effectively.
Last edited by pmmpete on Thu Jul 10, 2014 9:40 pm, edited 1 time in total.