Here's a shot taken of the bottom of my cab with DRY Gloss POR-15. You decide whether it's glossy or rough.
...and here's a shot taken of the floorpan area after using POR-15 followed up with several coats of Krylon Semi-Flat black, while the POR-15 was tacky.
fordman is correct...you don't use a bristled brush, you use foam brushes/rollers. I used the small foam rollers on virtually everything except the nooks and crannies, and the foam brushes worked great for that. You don't really need the rollers, though...the brushes will work just fine, and any brush strokes will smooth right now. You can pick these up for next to nothing, which is good since each brush is single-use-only.
I did my inner fenders with it too, after sandblasting and proper prep. They turned out great.