Cons I have found in the game:
--Minions just won't shut the hell up. After a while their constant generic shouts during combat get annoying.
--No fast travel. No really, I liked this at first. But the quest hub often sends you to the same area's multiple times, and monsters respawn quite quickly. So you'll find yourself fighting through the same groups of enemies in the same places over and over again. It's all just unnecessary padding.
--Directions can be a bit confusing at times yea. Nothing too bad though.
As for your concerns:
--You won't miss mounts. Running is fast enough. Fast travel you will miss after a while, probably.
--The story is pretty generic, but it is there. A nobody becomes a 'chosen one' through means that are out of their hands, rises up to become a hero, etc... Plus the story feels very contrived here and there.
--Yes the game can be challenging at the start. But it's really not that bad if you're not brain dead. Best to start out as a warrior, as even though you can level all classes with one character, your base stats are determined by what class you are when leveling up. So you're a warrior and level up? You get more health/defence. You're an archer, you get more attack that level, etc. There's a page on it on the wiki.
--I've never had too much trouble with bugs. Even when I bought it on release day. So I wouldn't woryr about it too much.
My own input:
The game really doesn't play as a JRPG. Sure you can tell that it wasn't western-made, as the writing style of the story and such is a little different. But otherwise it's just like a western RPG imo. The game has some faults, but those pale in comparison to the gameplay. Mini bosses and boss battles are awesome, to say the least. Heck, even the 10th Chimera I fought still felt pretty awesome. Nights are great too. It's truly dark outside, and can be a bit scary with the increased monster spawn. Not to mention the spells for mages/magic archer, and the climbing onto large enemies' backs to attack for melee characters.
It's definitely worth buying and playing, in my opinion. A very unappreciated game, considering how much I heard about it on the net before and shortly after release.