I have one and used it this year in the summer on my boat. It does burn through the phone battery fast, so a charger is needed for all day use. I did not use it to mark fish, but to plot bottom contours for Navionics, and had hoped to use it to find good holes and spots to ice fish, although I have not gotten out yet this winter. I like it, but I do have 2 other fish finders on my boat for larger screen and better fish marking, so I may not have given it the full attention that someone using it alone may.