Never used a flasher on the ice before, so I bought a 176 last year and used it pretty exclusively for lake trout. Had no problems seeing a 1 ounce jig in 90-180 FOW.
Basic GPS functionality, you can set way points, but don't think you can get a latitude / longitude reading from it, or ar least I never figured out how to.
I would throw a disposable hand warmer betweend the battery and screen to keep everything warm - not sure if necessary, but kept my mind as easy.
On my first outing the battery only lasted 3 hours, but then after fully charing it, I could go 8 hrs with no problems.
I already have a 597 unit, so I spent some money this summer to buy a second bag and shuttle, so I'll be bouncing back and forth between the 2 units. I'm thinking that for shallower fishing, the circular flasher mode on the 597 may be easier to use.