We went via lake chad. Its not to bad. Tracks are really poor, first part is following tyre tracks and that was quite nice but then pick up this really bad "road", massive washouts. just need to allow time. Not particularly hard to drive unless you go to fast. We did and crashed, bending our front axle in the process. Some of the washouts could take a 40ft truck and you would only just see the roof. Rough camping is great round there, we just camped a distance from the tracks but the villages aren't that great. We got robbed and stoned in Massakory, good place to stay clear of. Other villages aren't so bad but the Chadanian people aren't the friendliest. Need to allow 3 - 4 days and then the drive is fine. Tracks out to Abeche aren't great but just need to allow time. We went to a great national park down in the south east which has very few tourists but lots of game. People there were nice and had a great time. Did pick up very bad diesel down that way through.
Scenery down there is really nice, security doesn't appear to be that bad, we did manage to stumble in to a Chadanian army camp that because they are on the edge of the disputed area were rather jumpy but we talked our way out of that. Easiest bet is to keep out of villages and settlements apart from when you have to go into them for customs, etc and then its pretty nice.