One summer day in my very early youth, I witnessed a great storm. Over the course of an hour or two, this massive thunderhead formed, a deep, angry, stealy grayish-blue bordering on black. I remembered that it actually seemed to be swirling. In its center was an eye, a patch of luminescent, mossy green through which I could actually see the rain within. It was positively pregnant with rain. Little bolts of lightning, periodic bursts of illumination, shot throughout it, with a menacing rumble. Beholding it, I was thrilled and terrified, the hairs on the back of my neck standing up, a kind of hysterical glee rising in my chest. When it broke, it rained so hard that it exhausted itself in minutes. I couldn't even see the street from the front of my house. Afterward, as the sun was setting, the color of everything was off: the sky a dull yellow, the streetlights burnt orange, the fireflies neon pink. The puddles of rainwater still left in the street reflected pink light, too. I couldn't have been much more than five or six at the time. And I know with certainty I have never been privileged with such an intense aesthetic experience in all the twenty years since.
All of this is to show that even as a child, I loved beauty for its own sake. I did not admire the storm or its aftermath because I was hoping it would give me candy or take me to the arcade; I simply rejoiced in the object of my love. Goodness, in other words, is its own reward.
The reverse, I think, is also true: evil is its own punishment.
And this means that it is probably imprecise, or at least unnecessary (because redundant), to say that Heaven is where good is rewarded and Hell is where evil is punished. Heaven is just where good is; Hell where evil is.
Let's think about this more carefully, though. In Christian theology, God is not merely good in the sense that we are good, i.e., evaluated with respect to some standard; God is goodness, i.e., He is the standard of goodness. Thus, good is its own reward because good has a name and a mind and a will and limitless creative power. So it may well be the case that Heaven contains other rewards, where God showers His beloved with material riches, prosperity, and comfort; but it is not necessary for it to be Heaven.
By contrast, in Christian theology, evil is imperfection, flaw, or defect. It has no objective ontological existence of its own. To give oneself over to evil, then, is simply to destroy oneself. This is telling because it illuminates Christ's analogizing Hell to a dump wherein garbage was burned: a place for broken and useless things. Hell, indeed, is where evil resides.
Here again, it is unnecessary for Hell to be painful in order to be Hell. But does that mean Hell isn't painful? Or that there's no possible way to reconcile God's goodness with the prospect of eternal torment? I think not. God's mercy is such that He does not permit His children to enter eternity under the delusion that evil is anything other than what it is, or that evil is capable of triumphing over good. He lets them go to the fate they've chosen for themselves, with the proviso that they understand it in the fullness of truth: that they have rebelled against good, and that evil cannot shield them from it. If pain, even the mere spiritual pain of having knowingly made a bad choice, results, so be it. (This is one of those points that I think is simply incomprehensible to the typical atheist: that pain is not an unmitigated evil but can be instructive, even instrumental -- and in this respect is actually good).