I went there last year, and visited the forts of Vaux and Douaumont, the ossuary, and the Citadel, along with the town of Verdun and the surrounding countryside. With the exception of the Citadel, it was all very worthwhile and interesting.
My beef with the Citadel is that you get into a small driverless train, and it trundles you along a kind of "WWI Verdun Experience" of mocked-up scenes with mannequins, videos and audio. If I had known it would be that I wouldn't have gone as I prefer to see historical places with as few added novelties as possible, although that is just my personal preference. Having said that after the little train ride there is a room that showcases genuine artifacts from the battle, which I found very interesting.
You really need a car to see the surrounding forts and other things around Verdun.
As for the town itself, it's quite pleasant (also quite disconcerting at first to see so many pockmarks on the facades, they never got round to filling them in - I suppose they were left intentionally after the battle as a reminder of the intensity of the shelling).
The countryside is very beautiful, and it's a sobering thought to think that a century ago it was a treeless muddy corner of hell on Earth.