It's funny but i actually like the ads on the trains in Japan and when I was visiting other countries who's transit systems had no ads I thought it was boring.

Some of the ads are hilarious. Some are for the services that are not common in the USA. Nintendo has some where they add in a trivia Q&A, the format being, Question->Ad->Answer and I usually find them interesting and I'm often happy to learn about whatever new Nintendo game they are showing off. Often there are ads for theater plays, concerts, museum events that I only find out about because I saw them on the train.

I also like some of the campaigns where they decorate an entire station or the entire train, the entire car.