I have the T-POD and I use it on the kayak. Same application on the phone/tablet. I haven't had a problem and it helps me locate structure in water. I will admit that I don't use it all the time. Depends on how well I know the area that I'm fishing.
It is a good unit for the price. Relatively inexpesnive, but you do have to invest in a cell phone or tablet to run it. When all is said and done you are nearing the price of a Lowrance, Humminbirde, etc.
A couple of issues I am having...... Drains my battery on my iPad in about 5 hours, iPad overheats on really sunny days rendering the unit useless, hard to read in sunlight causing me to crank up the brightness and in turn creating more heat plus draining the battery.
All in all it is a decent unit that is worth a try if you already have a good tablet or cell phone.