First off, the nudity. Common Sense makes it look like it's a big issue, but it really isn't. To tell you the truth, there's only two (or three if you count inhuman figures with completely pale skin) scenes with nudity of any sort, and one of them doesn't show a thing. One of them does show one breast, but it's very brief. I guess if you have a problem with drawn breasts, then it might be worse, but honestly, breasts pop up in art all the time.
The language wasn't that bad. A few s**ts and one f**k, but other than that, nothing drastic.
Of course, this film takes place in the sixties, so there's a lot of drugs and alcohol, but it isn't really a big issue.
The violence is probably the biggest issue, and to tell you the truth, it's nothing to worry about. A few scenes regarding the Vietnam war, with some blood, but no serious gore.
I actually think this would be a positive experience for your children. It can really teach them a lot about music, art, politics, and love. Definitely a thumbs up.