Jalapenos do take a long time to ripen (turn red). That is the main reason you rarely see them red. They are picked in the green state most of the time. There is probably a bit of taste difference and likely a bit more heat with the full ripe ones. It is up to you if you want to wait around or not. I pick them when the reach mature size. At some point they quit growing and just sit there until one day you notice a bit of color change and quickly thereafter, they will be red. Just like any fruit, as it ripens, it will soften. The key is to pick them just before they start going soft. I have let them go red before and they were still relatively firm, but I never waited very long after that. They will still be fully edible if they are just a little soft, but I wouldn't leave them on the plant once they start softening no matter what color they are. Good luck and enjoy them. A good mild to medium pepper and they have good thick flesh.
Bruce

Concur: A ripe Jalapeno will have a bit smoother flavor, But no additional heat. If field ripened, they do not soften quickly.

That is the reason red Jalapeno is sold at much higher prices than green. So are the re bells in comparison to green once. To me, some younger peppers are tastier than fully matured. Peppers are not like tomatoes that have to be ripen to be harvested and consumed.

Peppers are not like tomatoes that have to be ripen to be harvested and consumed"

Ahem... Fried green tomatoes? Green tomato salsa?