Must say that I have upgraded to a Zumo 590 but much prefer the display on the older Zumo 550.
I don't want to see the speed limit and other information that is squeezed into the 590 display and is for me not easily read.
Isn't it strange how requirements for a simple navigational aid can differ so much? For me, the speed limit is one of the most essential pieces of information on the screen while I'm on my commute in town. With so many changes of speed limit, with my eyes on the other traffic, pedestrians etc., my mirrors, doing lifesavers and me riding to the conditions, it's really useful to know where I can instantly find the current limit when a plod speed check/camera comes into view.
I like to think that I know the speed limit where I'm riding/driving without looking at a satnav.
I do too and for 95%+ of the time, even commuting in London, I do, but there are so many changes of limit that it's very easy to miss one and sods law says that's the one with the speed trap/camera in it. Signs get obscured by parked vehicles, other road side furniture, vegetation etc. and gone are the days of "street lights so it must be 30mph". Doing exactly 30 in a 20 zone is well into points territory.
I just wish the sat nav would also tell me if I'm allowed into any particular bus lane because that's another mine field that's already cost me £60 when I missed the sign.