I am fairly new to quilting, but I love my June Taylor slotted ruler. I have a 87% chance of cutting my strips straight now! (I just made up the percentage, but I have tried cutting 2 1/2 inch strips without it. I can't do it.)
And, yes, I have torn up the little tear drop openings, but I am okay with that. Just makes it easier to fit the blade in the next time. :)
My sister has been quilting for 12 years, and she tells me that sometimes you just have to buy a new one, but so far I don't see that in my future.