So I got this sweet, sweet game yesterday and boy is it awesome, I got it for PC of course and it looks so amazing, but although I love my mouse and keyboard using the controller further away from the screen allows me to enjoy the hole picture a lot more and the game looks even more gorgeous and feels way more cinematic, hence my predicament... I suck at playing with the controller. 
 
Like I said I go with mouse/keyboard all the time and Im not used to playing with a controller, specially for anything that requires aiming, so my question would be: 
If I took the time to get better at aiming with the analog controller would I eventually be at even ground with using a mouse or would it always be slightly worse?.  

I suspect the latter, which is why I never bothered to try, but I think this game is worth it. So let me know what you guys think.

Controllers are somewhat less precise than a mouse, regardless of who is using it. If you played with a controller for a while though, I'm sure you'd do just fine with it.

As a PC gamer with about 110 games on the xbox 360 i can say with some level of confidence that the xbox 360 controller (despite it being the best controller i've ever used) isn't up to the task of being on par with a mouse and keyboard. 
 
I don't honestly believe any controller ever will but i would like to be proven wrong ^^

Generally it is harder for a KB&M gamer to learn how to use a controller than it is for a controller gamer to wrap their head around KB&M.  I'm pretty good with both ways of playing, but I've gone back and forth between methods for a long time now.  I think you could probably adapt to it with enough practice, but I have no idea how long it would take, and you might not ever feel quite as competent with a controller.