I use memory map on a nexus tablet on one of those screen clamp thingys, my eyes are not that good and I find driving round with reading glasses on the bridge of my nose a bit of a pita, will be upgrading to something bigger one day.
Another point, if you buy memory map don't get the HD version if you're putting it on a nexus, the HD version is 13GB leaving little room for owt else if you put the whole UK on like I did, you can chop bits from the whole uk map to make a smaller maps, but it'd be easier to get the standard version at 3GB and just have the whole country on IMO, that's what everyone else I've been out with seems to do.