Also, due to the bell curve nature, just over 80% of your results will fall in the range of 7 to 14. 90% fall from 6 to 15.
So, depending on how your DCs are set, if you lie anywhere near either end of the RNG, you'll be sitting at near auto success or auto failure.
For example, if you need a natural 6 to hit, on a d20, that's a 75% chance of success. In this method, it's a bit over 95% (also note that getting fiddly +1s here and there at this point have a negligible impact on success). Likewise, if you need a natural 16 to hit, it's normally a 25% chance of success on a d20, but it's less than 5% here (although getting small +1s to push you toward the center has a much higher impact).
Also, if someone is hanging around just above or below the middle of the RNG (say around 8 or 13), a +2 bonus or -2 penalty has a much bigger impact on success. For example, if you need a natural 8 to succeed, you have an 83% chance of success. A +2 bonus gives you a bit over a 95% chance of success (a net shift in about 12%). A -2 penalty gives you a 62% chance of success. That -2 penalty just hit you by over 20%! So, against NPCs that are likely hanging around the center of the RNG, a debuffer will be brutal, and buffs on the party can be really strong.