I’ve been messing with the Humminbird FishSmart app. I purchased a lake near my home a fish frequently to test it out. I’ve used it seven times so far while fishing; it crashed hard once requiring my phone to go through a double reboot and has needed phone reboots to track my location three additional times. It seems to me that it tracks location poorly unless you’re leaving a trail. Also, buying individual lakes @9.99+ each is a tad spendy and their terms of use read to be for a limited time. The Lakemaster map quality and features for the available lakes is nice if you’re willing to pay.
Navionics is an infinitely better deal. The maps are pretty identical for many locations.
I was reading recently that the next generation of smartphones will have far better GPS capabilities compared to what is available now.