I've been using OSMAnd almost exclusively for close to ten years. I would describe the app itself as rough but adequate. There are a lot of settings you can poke at, and the way you navigate through the menus of the application to poke at those settings has never been particularly streamlined, however it gets the job done for me.

The map data itself is superb though, with the single exception of having inferior (relative to gmaps) data about businesses. Many businesses aren't mapped, or don't have their open/close hours listed or up-to-date. For this sort of information, I use a web browser and search engine to look up the business's website. For gas stations or restaurants while traveling, I do it the old fashioned way. I look for signs along the side of the road using my eyes. The same way I used to do it when I first learned how to navigate using AAA road atlases. It may seem old fashioned but it's just fine for me.

In other respects, the OSM map data is very detailed and I love the aesthetics of the OSM tiles. In particular, OSM maps are far superior to gmaps in places like parks. In places where gmaps simply says "Whatever Park", OSM will have park benches, water fountains, picnic tables, etc all accurately mapped to within a meter. It's earnestly impressive and very useful. I think gmaps excels at mapping businesses because that's where the money flows, but doesn't give a single damn about useful things like water fountains because water fountains don't buy ads.