One of my problems with SR4 was that many - maybe most - of the cool metaplot and setting stuff - such as Saito, the Arcology, the Bugs and so on - were already resoplved, and the newer metaplot was less evocative. Most of the cool metaplot stuff was already resolved. I actually think that the 2050's were cooler, in terms of look, feel and metaplot, than the 2070's.
Also, guidelines to what could be hacked and when would be very welcome. SR4 had the feeling that "everything could be hacked", right down to your foe's smartgun, and hacked by wi-fi, no less. Clearer rules and guidelines about what hackers could do (with examples) would be very useful indeed.
Actually hacking the smartgun was used several times as an example in the books.
Generally everything which can receive wi-fi signals (has an open port so to speak) can be hacked provided you are close enough depending on the signal strength.
They are currently reprinting all the 2050 stuff as PDFs so if you want to play that just get them (if you don't want to take your books with you).
I can't comment on the metaplot as this is a matter of taste. But with StormFront a lot of the 4E meta got resolved and there are several new plots on the Horizon.
The Bugs are back, so are AIs (It is hinted that Deus is still somewhere) and Aztechnology had some serious victories. Also the HMVV infection is getting worse.
Matrix rules will be overhauled. They will still be wireless, but a bit more compartmentalized.