There is a lot of debate on this topic. From my experience, I would say that this is more or less true. I say this because even if you spend the extra time and get the first few correct and then get a lot of later questions wrong, you can still end up with a rather low score.
The key is to find a right balance. Granted the first ten questions are important, but if you spend over 3 minutes on them you will stress out on later questions.
I have heard that to get a better score it is wise to spend more time on the first ten or so questions, even if it means rushing through the last few. Is this still a valid strategy? Based on my results from GMATPrep and PowerPrep, it seems to hold true. Did this strategy work for you when you wrote the actual GMAT?