I have the same phone and after messing about with some of the free apps I bit the bullet and purchased a copy of viewranger, having used it nearly evertime I have been out now I can happily say it is hands down an excellent piece of software. Gives you the full functions you would expect from most if not any gps handhelds, along with the usual trip records and such that you can then make into routes should you wish to do the same route again. This also means you can download other routes onto the phone to walk and such, there are options to add images or POI's to spots on a route along with a handy panorama feature from the map centre, so if you are planning a route and want a more visual cue on the hills instead of your standard map lines you have it there.
The pc software for the app allows you select various OS sheets for purchase and handily lets you pick only the parts you will need so you can mix and match sheets to fit the minimum order amount.
No affiliation to this company just a very satisfied customer.