I have used the older Bottom Line Fishin' Buddies and they are not very reliable; I've had to send several of them back for repairs. I now have the Humminbird 140c and it is a far superior product, even though it looks very similar. As already mentioned, the electronics are sealed from moisture, which was a design defect in the Bottom Line models. The SideFinder feature is very, very useful and well worth the extra cost, in my opinion. The only problem is that when the SideFinder view says that there is a fish out there in front of you, maybe 38 feet out, you don't know how far below the water surface that fish is, but at least you have some confidence that there is a fish out there. However, it may mark a fish, when what it is spotting is actually a floating weed clump or a floating piece of reed or your fly line, so don't take it as gospel. Also, there are many, many times when you'll hook a fish that never showed up on the SideFinder view or straight down view. As others have mentioned, this unit is very useful for determining depth, especially when exploring a new lake. Even though the 140c has the color screen, I'm not sure that it is worth paying extra for the color screen, which uses more battery power, but it looks nice. I've never used the unit for determining the thermocline, as Kevin has done, but maybe I should look into that. When I fish lakes where the thermocline has set in, I can usually determine where the thermocline is located because all the fish are located at that depth, which is usually in the 18 to 24 depth range. I have had no problems using the Fishin' Buddies on either float tubes or my pontoon boat. For the pontoon boat, I attached the included C-clamp to my seat frame, on my left side next to my left knee and that seems to work out well, although my seat frame has square tubing so if you have round tubing it might be a problem. Some fly fishermen will accuse you of cheating if you use a fish finder, so be prepared for that. I have a friend who thinks using a sinking line, sink tips or weight on a fly are all cheating, so there are all levels of cheating in this sport.