"TAKE... YOUR... MEDICINE!"

A shot to the HEART,
the trolls to BLAME!
changing the face,
Of this GAME!

Adepts also get the metamagic ability to increase power points or shift attributes dependent on their initiate grade. This makes an adept frighteningly effective. I have mixed feelings about attunement...

Actually, adept metamagic could be better - it's by far not on par with what the mages get.

By RAW this is quite true.
This is however an area that is ripe for house powers / house rules.
AH has an intriguing SR3 example on his site.
Metamagics often change how certain rules operate.
running with that as a baseline:
Trading Stamina for "Bullet time"= 2 stun for a free action, 3 stun for a standard action, can only be healed through rest
Power pool = add up to [Magic] dice split amongst tests using an adept power, refreshes with edge
Magic fist = use magic instead of strength

As adept powers are extremely specific, it limits what metamagic is available to niche items,
but my imagination is my only limit.

It always come down to the small marginals. An adept does not have to be a kung fu combat wombat - gunslingers, social adepts, stealth adepts and a myriad of other kinds can be built, and whether or not they perform better than their augmented mundane peers is a matter of circumstance, intelligence and setting.

Weren't we just talking about how Adepts already outpace Sams considerably?

Combining Adept Centering, Item Attunement, and Infusion can fairly easily give an adept a DP bonus basically equal to 2x initiate grade for the more difficult tasks like doing up the HV thing or 3x Initiate grade for shooting 4 guys in a pass with 2 guns or the like.

I guess they may fall short when compared to a well Initiated Mage, but so does everyone, so that's hardly the Adept's concern.

Adepts are better off in the long run, but I'd say it's pushing it to say that they considerably outpace Samurai, since that to me implies that a samurai outlives their usefulness rather early, a situation which generally clashes with my personal experience. They have definite advantages and in time they can do things that mundanes plain cannot hope to do, but out of the box they struggle to be as good generalists as a cybered up norm. Which is fine, really-- in a best case scenario, specialists rule all because everyone just tends to stick with what they're good at when given a choice in the matter. A team can find uses for a Silent Way Adept with 13+ dice in the entire Stealth group and Commanding Voice even if that is the only stuff the character can actually do (and it shouldn't be). But with Shadowrun being what it is, there's something to be said for having a guy on the team who spots targets through walls AND is fast AND stealthy AND tough AND has even odds when cracking a maglock without even falling back on his 5 Edge. Heavy cyberware and raw attributes are very hard to beat when it comes to getting as much dice as you can in as many pools as possible. An Adept can be very, very good at a few things at once, and Adept Centering is awesome, but samurai are hardly chopped liver.

Just to nitpick, but you do not always net karma. When bad turns to worst and they burn the edge, then usually that run is net karma loss...