Modrana really is worth a try. It has big easy press buttons ideal for use while driving; one touch reroute (works flawlessly even when you go wildly wrong on purpose); x2 and x4 map scaling options - again, great when driving so you can see street names easily; integrated POI search/store (with custom query); voice guidance with onscreen instructions I'd already mentioned. Also fully working auto rotate and map centring around current position. Oh, and it works with downloadable tiles by default, but development is underway on storing downloaded map data to sqlite dB (much more efficient/compact disk space usage).

But best of all is the developer, who is a real good guy, always willing to fix/enhance and provide detailed feedback & help. I'm not involved with the project - just a very satisfied user who greatly appreciates MartinK's (the dev) ongoing efforts to deliver what people actually want/need. The word "proactive" has been hijacked by bullsh¡t bingo, but it trully applies in this case :-)

Have a look here http://talk.maemo.org/showthread.php?t=58861