Yes the basic map you get with it is rubbish. This is the page you want from Frankie's files
http://www.aukadia.net/gps/lwg_32.htm which will put OSM maps on your Etrex and when it's attached via the USB this will show in Basecamp (I keep meaning to put it on the PC as well but haven't got round to it) be sure to follow the instructions carefully especially the bold and it will load okay (there is a section which describes the part of the process that most people get wrong and I ... you guessed it
). Whichever method you use of creating routes, tracks etc getting a decent map on the unit is a good starting point.
The other alternative is to buy maps and I see that a number of people here have bought the Garmin City Navigator map, my understanding is that this will work better with routing and turn by turn instructions but I find OSM works very well so I'd suggest giving that a go in the first instance.
I got my E30 for Christmas and by New Year I thought I'd made a big mistake and wanted to bin it, now I'm very happy with it and still learning and exploring the 'best' routing method.