Guru Rinpoche said: we need an unfabricated Dharma. Impermanent or permanent are fabricated concepts.
This means the fruit of the practice, seeing reality as it is. By no means this denies that all compounded things are impermanent. The unfabricated Dharma is Sadharma, the fruit of the practice of Buddhadharma. There's no such thing as an unfabricated Buddhadharma. The difference between them is the same as the difference between the moon (Sadharma) and the finger pointing to it (Buddhadharma).
I found this:
"The idea that perceiving impermanence is the key to happiness also doesn't make much sense. It's not something that can be understood by intellect alone".
http://buddhism.about.com/od/basicbuddh ... anence.htm
Perhaps posting the whole paragraph makes it more clear:
The realization of wisdom is that this separation is an illusion, because permanence is an illusion. Even the "I" we think is so permanent is an illusion. If you are new to Buddhism, at first this may not make much sense. The idea that perceiving impermanence is the key to happiness also doesn't make much sense. It's not something that can be understood by intellect alone.
This means you must gain insight about it, not just having intellectual knowledge that all compounded things are impermanent. Knowing intellectually that all things are impermanent doesn't lead you to think, feel and act as if they were. While you know intellectually that things are impermanent, you live as if they weren't, so suffer when change happens, seek happiness where there's no happiness and, above all reify the "dream like reality", including your own self, thus planting the seeds of samsaric experience at its deepest level (avidya).
So this idea may not make much sense at first, but later on makes a lot of sense, even intellectually. However, when contemplating this thought you will gain insight about it. It's remaining with this insight that helps you getting closer to the fruit of the practice of Buddhadharma.