[0B]

Oh yeah, sustaining spells is a thing I've always liked: you have to remember every spell you're sustaining, or they'll stop working.

Oh man, I've always done that part of the work on GM end (Prompting players to sustain their spells or not), but I like that a lot better.

[topcat]

Drain-based magic
Separating defense from soak
Contact loyalty and connection ratings
Street cred
Build diversity

EDIT: more thoughts

[Reaver]

Drain-based magic
Separating defense from soak
Contact loyalty and connection ratings
Street cred
Build diversity

This hits most of the points for me as well.

I play other systems regularly, But these are the points that stand out for me about SR... 

[PiXeL01]

Player since early SR2

Magic, unlimited until you tire out.
Grounding, cast a physical spell through an aura from astral space and see the spell ravage the casters companions.
Astrally active when using magic; magic may be strong but if you are sneaky enough you can punish a user the very moment they use their talent.
Force, any force at any time but pay the price (although 2nd Mana Dart > any other combat spell save Grounded Hell Blast

I miss the old Combat, Control, and Magic pools. Meant you needed to plan more to reverse dice for later.
Also Karma Pool which I think is better than this new (4/5) edge thing :,(

The initiative system, though I think 3/5 is a vast improvement to 1/2.

Riggers, being a vehicle, how awesome is that!?!

[Chalkarts]

One of my favorite things has always been Magical Drain.
It just made sense to me.
I loved the fact that the mage was in full control of the magic and the power of it.  A magic throwing everyhting they had into a spell to save the group and then collapse in pain from the drain always made magic feel more "real" to me.

I know a lot of people thing SR5 was too crunchy.  I'm not one of them.  I like the detail that the crunchiness provides.  As long as the GM is proficient with the rules, the game can run smoothly.

[Crimsondude]

I miss Combat Pool