It's probably just high usage, live isn't just the 2million+ new Xbox One users but all the old 360 users as well. We should also take into account any WP and Windows Xbox live games in use to. At least it hasn't crashed fully or anything.
Live for the 360 lives in a different environment than Live for the One (which resides on Azure)...
Live for the 360 still resides on the Redmond campus, in almost the same spot since the OG Xbox days.
The 180update knocked Microsoft off course, rather they admit it or not. And it seems that they are behind schedule with how the One and Live should be functioning.
I installed NBA2K14 from disc and it did take a while (about 45min - 1hr). Demos (FIFA, NBA Live, Dead Rising 3, were fast. All within 1/2hr or so. And i only got a 25-30 down/up connection.
All my Arcade titles Peggle2, Max:CotB, Killer Instinct:UE, were very fast as well.
Notice that updates take forever. NBA 2K14 had a update the other day, and it seemed like an eternity to install