I'm looking at the 3 ways to do damage in SR4:
1. Physical (ranged/melee) combat
2. Direct Combat spells
3. Indirect Combat spells

Let's judge these each on the following categories:
1. Cost - how many BP or how much karma does it take to be effective with this?
2. Repetition - how many times can you reuse the same effect?
3. Output - what is the potential for an average starting character to do with this?

1. Physical combat
This is the cheapest in terms of BP, as most of it comes from the gear you have. The skills for this are fairly commonplace, since you don't need a quality to get them, and you can fit most physical combat gear within the 5000Â¥ you get for 1 BP. Depending on what weapon you're using, you can use it as often as you're in melee with the target (for melee weapons) or until your clip runs out, which is probably once every few Combat Turns if you're using full bursts. It has the least damage potential, though, because ballistic armor is typically higher than impact armor, and even with AP there's still a significant amount of damage that can be soaked, despite having a rather high base damage.

2. Direct Combat spells
It takes being a Magician and having good Magic and Spellcasting to be any good with any kind of spell, and an additional 3 BP or 5 karma to learn the spell in the first place, but once you've made that investment, you're good as gold. Direct Combat spells don't quite have the repetition potential of melee weapons or even some firearms, but they've got some of the lowest Drain values of any spell in the book, so they're inherently likable and easy to soak - anyone with 12 dice for Drain (not a hard feat once the Centering metamagic gets thrown into the mix) can easily soak a Force 11 stunbolt or a Force 9 manabolt. This, though, has the highest damage potential, since even with counterspelling, the attacking mage is usually going to get at least 1 net hit because pools to cast are much, much higher than pools to resist. So that Force 11 stunbolt deals 12S, and one guy is down at the cost of a single Complex Action. No damage resistance involved, nothing past the spell resistance test, and no drain (on average) taken. It's win-win for the magician.

3. Indirect Combat spells
Once you've dropped the BP on being an able caster, these appear automatically as inferior to Direct spells for several reasons. First, for the same cost you get something much more effective in a Direct attack. Second, the Spell Resistance test is based on Reaction, which is typically higher than Willpower for most characters (and has the potential to go higher - there are very few things that augment Willpower), and even Body for anyone who's not a troll. On top of all of that, if it even is successful, your damage gets to be soaked by Body + half Impact armor, and if it has an elemental effect (which so far all Indirect spells do), you can also add in a protection rating from some armor modifications if you have them, which may even let you exceed your original Impact armor total if done right. On top of all this, the Drain values are high enough that a mage with a Drain Resistance pool of 12 would only be able to cast a Force 3 lightning bolt before taking damage himself from the Drain involved. All in all, the cost is the same as Direct Combat spells, but you lose out on damage output and on repetition, as you're going to need to keep zapping yourself to do much damage.

Summary:
1. Cost - Physical combat clearly wins out on this one. There are so many ways to increase your ranged attack dice pools that it's not even hard anymore. It's also much less of a BP or karma drain than is any form of magic.
2. Repetition - This is almost a tie between Direct Combat spells and physical combat, but Direct Combat spells have just a slight edge here. With physical combat, you need to be in the right range and, if you're firing a gun, will need to eventually switch out your clip, which eats a Simple Action + a Free Action if you're using a smartgun. You can just spend that Complex Action each turn to keep churning out that Direct spell at almost no Drain - basically, you'll only take Drain if you're unlucky. Indirect Combat spells with their high drain lose out on this category, since your ability to cast them will degrade rather quickly.
3. Output - Physical combat would win here if it weren't for the Damage Resistance test most often using Ballistic armor. No, here again Direct spells win out, since they don't allow anything other than the initial Spell Resistance Test, and if that goes well for the mage (which is the typical outcome), they can end a person without much effort. Both Indirect and physical combat allow you to soak damage, which puts them at a minimum of 1 DV disadvantage, and more often along the lines of 3-5P out of luck.

Conclusion:
Although the cost is high, based on both repetition and output, direct combat spells are superior to physical combat in a good majority of (but not all) cases, and always superior to indirect combat spells. This just doesn't sit well with me, and there is no good balance mechanic for it in SR4 that wouldn't gimp indirect spells also. Which brings me back to my original post. In order to make Direct combat more reasonable, there needs to be some balancing function in them, and I believe it would be that the spell deals base damage of (F/2). This might be less than the damage of physical combat and indirect combat spells, but take into account that first, the target of the spell only gets one roll to defend, and second, the drain is very easily dealt with for high Forces.