I haven't started a SR4 campaign yet, but by the looks of it spirits look almost impossible to deal with unless you have magical support. One way of dealing with them is of course to have magical support always, but that seems silly in a lot of encounters that the NPCs always include a mage (or be able to call in astral support).
A standard Force 5 spirit seems almost to deal with - it has 10 points of hardened armor. The few options to deal with that as a mundane that I can see
- Sniper rifles, shotguns and grenades have the DV and AP to take them down.
- called shot +4 DV and a bit of luck, you can take one down with a heavy pistol.
- Ex-ex or APDS ammo.
- tasers, stun batons and stick-n-shock have -half AP, being able to penetrate their armor.
It still seems like a lot of effort to take down a spirit before it does a lot of damage(especially with Engulf seriously impeding the enemy's ability to fight back), and a mage could sit back and each time the spirit dies, just summon a new one and send it against the enemy. Of course there is drain to worry about, but spirits still seem like a very risk-free way to do a lot of harm.
If you go into higher-force spirits, it quickly becomes impossible for anyone in a reasonable way to counter them, but I guess that the spirits using Edge to resist the summoning is a good way to handle that.
On top of that spirits have a whole host of other cool powers.
Those of you who have been running SR4 campaigns, what are your impressions of them? Do the mages just use them to get everything done? Do they leave the street sams feeling envious of the spirit's sheer durability and combat power? Are you using house rules to keep spirits in check?