The warmth of a campfire takes the edge off a winter or early spring backcountry trip. In the summer season a campfire should be avoided.
I try to avoid having a fire in the backcountry. The main reason is that a fire gives off carbon dioxide, and I am serious about lessening my contribution to global warming. I often go all summer long with just my Whisperlite stove for cooking and warmth.
In winter and early spring however, a fire to take the chill off a cold evening or early morning in camp is a joy to have. I have read somewhere that fire is the rose of winter.
Starting a fire is not hard when the weather is dry. Just gather a few twigs and dried grass as kindling. Have some finger size sticks ready to feed into the growing flame. If it has recently snowed or rained, the best place to find kindling is at the bottom of evergreens. Break off some of the tiny dried branches at the base that have died from being shaded. They are usually the driest ones you will find in such conditions, being above the snow and protected from moisture by the canopy of branches above.
A small Bic lighter makes starting a fire quite a bit easier. If it is very cold warm the lighter first by holding in against your body or place it under your armpit for a few minutes. I sometimes splash a little bit of stove fuel to get the fire started quickly.
It also is smart to bring a long some fire starter sticks or paste, in case it has snowed or rained a lot, and starting a fire is darn near impossible. (I have seen conditions like this).
Let me reiterate, in the summer season there is rarely a need for a campfire. Also, avoid having a campfire in heavily used areas, where there is little available fuel. A fire should not be considered in desert or alpine areas where wood is scarce.
Be very careful with fire in dry areas. You don't want your name in the paper from having started a wildfire - that's the kind of publicity you don't want. Always build a fire on inorganic soil. Creating a pit for your fire is a good idea to keep it from escaping. If you are camping in snow, dig down through the snow to solid ground before you start you campfire. Otherwise you will end up with the slowly sinking fire, put out by the snow it is melting into.
Always make sure your fire is out by placing water and/or soil on it. Put your hand into the middle of the fire charcoal to make sure.
In winter time I like a campfire as much as anyone else - sitting next to it in the morning as the sun slowly climbs to warm the day, holding my hot chocolate.