Is Nimzowitsch's My System out dated?

Are the ideas in My System out dated or do they still hold weight in the modern game?

yes .  

Many concepts hold, but some better than others : for example what he said about rooks on the 7th and passed pawns is still completely valid, while his concept of overprotection hasn't really stood the test of time, and his ideas about openings are a bit too rigid (not to mention the examples are not 100% convincing).

Watson's Secrets of Modern Chess Strategy contains a complete re-assessment of Nimzovich's ideas, though it may be more confusing than anything else...

+1. Excellent follow up on My System.

The short answer is no, it's not out of date.

Hicetnunc references an excellent book that should be read after you have studied the original. It's not meant as a replacement for My System, but an explanation of how chess has progressed since then.

Think of Watson's work as volume 2. Yeah, it's that good.

Interesting thanks guys. I had wondered about overprotection and whether it should actually be the leitmotif behind all strategy as Nimzowitsch claimed - it's interesting to hear that it hasn't stood the test of time. Thanks for the recommendation of Watson's book. I've finished My System but plan to work through Chess Praxis next. Perhaps it would be a good idea to read Watson's book after that.

Personally, if you've really studied "My System" and not just casually read it in a weekend, then you can probably skip Praxis and go straight to Watson. But you get out what you put into "My System".