This thing has no equal on speed in the water, just be very careful after investing points into it since the lag can cause some things to appear right when you are on top of them. Also they are very squishy so a pack of jelly fish will usually spell the end for it if you get caught.
MOBILE PLAYERS: I have tested it, and NOTHING, I mean NOTHING attacks you. This includes jellyfish, anglers, mosas, megs, EVERYTHING. HOWEVER. This only applies if you DO NOT attack the thing in question (or ammonites), and in my experience this makes it perfect for scouting out high-level potential tames