Just like any northern New Jersey freeway, I-280 suffers from heavy truck traffic and a dated design. Particularly bad is the section from the Garden State Parkway eastward. Eastbound through traffic MUST merge right at least one lane in order to stay on I-280 (thanks to the unbuilt NJ 75). More than half the highway is lost, creating a traffic chokepoint as five lanes are whittled down to two, and then traffic is on the 1950's-vintage NJ 58 viaduct, featuring quick on-off combinations and a lack of merge lanes. After the NJ 21 ramps, each with STOP signs, merge onto the highway, it crosses a DRAWBRIDGE, and finally the highway gets better.
Westbound, traffic doesn't know the right lane is EXIT ONLY until the drawbridge, at which point there are about 300 feet left to merge into the two NJ 58 viaduct lanes. The same problems are faced here as on the eastbound side, but a new problem arises at the Garden State - both of I 280's WB lanes at the EXIT 13 (dead NJ 75) merge become EXIT 12 lanes! Again, traffic is forced to merge left, though with three through lanes the situation isn't as bad as eastbound at EXIT 13. Overall, the old NJ 58 viaduct is by far the worst problem, though the steel-grate Stickel Drawbridge doesn't help. Both of these are long overdue to be replaced, and while the NJ 21 interchange is about to be reworked to finally accommodate all traffic movements, the replacement of the old highway is still only a long-term plan. If not for NJ 58, I-280 would have scored much higher on safety and congestion.
The other major problem with I-280 is the signage, which just plain stinks east of EXIT 8. There are no exit tabs on all the old signs above the depressed freeway through Orange and East Orange, and advance signage is very poor (except for the Garden State Parkway). Also, because basically every street in the Oranges has an overpass over I-280, the sight distance on the highway and to overhead signs is atrocious, so it's easy to miss the one sign with the information you need. If you don't know where you're going, it's easy to get lost. Finally, EB at Exit 17, the right two lanes have an overhead for CR 508 EB and the Holland Tunnel, while the left two lanes have... an overhead for CR 508 WB. There is NOTHING directing you either to stay on I-280 EB or toward the NJ Turnpike, so if an out-of-county motorist were to try to follow 280, it is more likely he would go straight toward 508 east rather than bear left toward the actual continuation of the highway.
To wrap up, repaving efforts have helped the western part of the highway, which was plagued with wet-concrete truck accidents on the two hills (First and Second Mountains), while the concrete through the Oranges is still holding up well.
Aesthetically, this highway starts out nice, but from EXIT 4 onward the scenery is suburbia, turning into a huge rock cut, followed by an urban depressed freeway, and ending with miles of industrial area on one side and train tracks on the other. This highway is some of the worst of Jersey, and only the fact that true traffic jams never happen saves it from being "The Worst Highway in New Jersey."