We have Garmin Nuvi and I like it. Routing is usually pretty good, although local knowledge saves a minute here and there. e.g. Dartford tunnel -> Southend it wants M25/A127, whereas M25/A13/A130/A127 is a minute faster and more pleasant.
We got it on recommendation of my nephews (both of whom have one) and after a while their mum was given a tomtom by work; that had a funny routing thing up on the A12 near where they live as it kept thinking they'd fallen off the A12 onto the road alongside.
I got a Germin Nuvi from Santa.
It is pretty good, and in terms of user friendlieness it is most excellent.
Annoyances:
1) The speaker of the unit isn't good enough to handle the Stroppy Woman's voice enunciating her 't's - and she says a fu*kload of the buggers, each time creating this high pitched horrible noise.
2) You have to really pay attention to what the display is showing, rather than wht the unit is saying in dense urban areas, as the Stroppy Woman doesn't really have any clue where you should be going and is just barking commands at you in the hope that her next 't' will burst your eardrums.
3) Stroppy Woman doesn't bark her commands enough in advance - the typical is coming off a motorway heading for a RAB. I imagine that most people would like to know what they should do at the RAB, at the beginning of the sliproad, so that they can get in the appropriate lane in advance, rather than dodging repmobiles still doing 80mph at the last minute.
4) Oh yeah, and you can't have your current speed displayed at the same time as the map screen. Arseholes.
It really does make me wonder who designs things like this, and if they were tested in the Real World or just on some lab based guesses, because thats what this feels like. A piece of kit that is oversimplified so that the over 50s can use it without the help of their children, that worked perfectly in a simulated environment, but is always one step behind a competant user in the Real World.
Those annoyances aside, it is a good SatNav. I appriciate the feature where you can add waypoints to a route, to force it to take you a particular route you want. I am getting on with it a lot better in Mute as Stroppy Woman doesn't bark useless orders at me, and I'd have to keep checking the screen to sort her lies from the truth anyway, so I might as well do it in peace.