Yea I feel you. I was using a Shure SM57 before, which is traditionally used for instruments. I read that Michael Jackson used that mic for Billie Jean, so I tried it out. It sounded good, but this MXL I bought has a certain warmth to it (probably because of the built in tube). It's not a HUGE difference, but it's enough to say "Yea, this mic sounds a bit better".
It is like any other piece of equipment though. If you don't know what you're doing with the BEST equipment, your final product still won't sound good. While a cat with a great ear will make the hottest shit with a $50 mic and a Casio keyboard.