I'd like to point out that Shotgun Choke/Spread is a rather overlooked rule. As we all know, a hit on the attack is generally worth three on the defense. With choke and burst fire, you can increase your net hits by reducing the defenders pool.
Narrow is the standard Flechette code. (+2dv/+5ap)
Medium spread hits up to two targets who are within one meter ofeach other. +0dv/+7ap, but -2 to the defense roll
Wide hits three targets within one meter, for -2DV/+9ap, but a -4 to the defense pool.
Multi-hitting uses the same attack roll vs all concerned targets. It also stacks with burst fire.
Let's take an AA-12(which has a gasvent2), put an external smartlink and an auto-adjusting weight modification on it, for 6 total points of RC while in FA mode, and see what a long, wide narrow burst on wide choke does.
The AA-12 is 7P/ap-1 base, so with that setting it would do 5P(+nethits) at AP+8, but also gives the defender -9 dice to defend. What that means, is the average runner is not even going to get a chance to roll. If the target is wearing any armor at all, they will almost always be taking stun damage instead.
Let's say the target is someone with a chameleon suit(6ballistic), with reaction 4, dodge4(ranged +2), and, say, an orc with a body of 5. He goes on full defense, and gets a single dice to try to dodge(4+4+2-9) - no hits, so he'll be getting 19(6+5+

dice to soak the damage.
Our shooter, on the other hand, has a fairly high agility due to some Muscle Toner 2 - say agi 7, a smartlink, and longarms 4(shotguns+2), and a Tacnet 1. 16 dice to shoot with the aa-12.
Buying hits: The shotgunner gets 4 hits on the attack. The ork gets no hits on dodge, and four hits to soak, and takes 5 stun.
Testrolling dice on my end: 3 and 5 the first set(3stun). 5 and 7 the second(3 stun). Which isn't too great at all, but it'd hit anyone nearby the primary target too. Its like a cheap grenade.
In the above example, changing to a narrow burst and buying hits, the ork gets 1 on the dodge roll, 4 on the soak, dealing 10 stun (5base+3hits+5burst). Which isn't bad at all.
Rerolling the above, two attacks for comparison, yielded 6/5 on the attack, 1/2 on the dodge, and 7/7 on the soak. So, 8 and 6 stun damage respectively.
That's an extreme example, though. For general work, medium-choke and short(or long+short) will serve you pretty well. Its also worth noting that due to the multihit rules, if you have some clumped enemies, Edge can let you drop a fairly large brick of damage onto all of them.
So yeah. Shotguns aren't great. But they're not too bad if you know the rules for them.