We are not pro-players to shooters or any other game, thus most maps are either to hard, boring or both. Otherwise we end up wasting our time in the few precious hours that we have together, trying out new maps that we know nothing about,just to find out we don't like them. I have to install and play the map a bit,or look at a gameplay. There's so many custom maps made by the community, however only few of them where actually any good (at least for us).
It's great fun, if i do my homework before the lan party. I've been playing Call of Duty World at War Custom Zombies maps for quite some time.