I like the space savings and the more classic look, honestly. Also the fact that it's four bars instead of five dots makes more sense; I can never use cel data successfully when I have one dot anyway. That first dot may as well not exist!
I remember being annoyed when they switched from bars to dots. The dots just looked weird! I'm used to them now and they no longer annoy me, but it's nice to go back to the bars.
One thing I wish they'd do (which they haven't yet even in 11) is to get rid of the extra "Personal Hotspot: 1 Connection" status bar you get when using personal hotspot, and just put the tiny hotspot icon with the number of users next to it in the blue status bar, which is what you see before you unlock your phone.
It gets to the point where I get annoyed turning on hotspot for people because that extra status bar pushes everything else down and makes the interface wonky in some apps.