The Philokalia has literally revolutionized my prayer life, my private life with God. It has opened my eyes and explained things that previous books only hinted at, only gave shadows of. I would highly recommend that you get a copy.
I've read books and heard sermons by men like Leonard Ravenhill, David Wilkerson, Paul Washer, Paris Reidhead and so on, yet their teaching does not compare to the wealth of insight that this first volume provides. I can only wait in anticipation for the next 3 volumes and pray that the translators hurry up and finish the last volume!
One word of warning though. If you are not a monk, then some of the advice cannot be taken on board. Some of it is extremely severe in terms of bodily denial, and in endurance and fastings and vigils. But even in this there are principals which can be taken on board and put into practice even by the busy husband and father.
A text I would recommend that is more specifically geared toward Prayer is, but is also based on the Philokalia (though contains many texts not found in the original series, and therefore of merit in it's own right and not simply a compilation of texts from the original series.) The Art of Prayer: An Orthodox Anthology