I don't play a lot of rpg's, hell, this was my third one after Star Ocean 3 and SMT: Nocture both of which I never finished, and I thought it was pretty fun. The learning curve is VERY steep, especially on the first boss, but that's because you have weak guns and aren't leveled up. I really liked the gun customization and customizing your outfits was kinda fun too. Also, there's a stage in the game that allows you to grind like crazy and also gets you a trophy, which is very nice.
Going to and from stages can be a pain, but once you figure out the teleporting part, it doesn't get as bad, or at least I didn't have any huge issues with it.
For $15, it's a must buy. At $20, I'd wait cause I'm cheap, but it's still a very solid game.