ProsPlotter: Outlining and planning is a good way to focus your writing and avoid the murky middle. This also prevents those random events that should have gone somewhere else but you don't realize it until your editor tells you. It cuts down editing time because you have to take a minute to look at exactly what your book will be about and how it will happen. Something that might have seemed like a good idea in your head may not look goo on paper, and you can delete it before spending the time to write the full scene.
Pantser: The creativity just flows! You never have to worry about running out of ideas, because when you sit and write at your computer the words just flow onto the page. Of course, you may experience writer's block, but we know it doesn't last long. Your stories are full of different aspects that you have no trouble extending to a second, third, or fiftieth book.
ConsPlotter: You lose a little room for creativity if you aren't careful. By no means is this a bad method, but it does take more time than pantsing, and a lot more planning (obviously). If you do feel like plotting is more your style, be aware of the trap of falling into your outline without room to be extra creative.
Pantser: The pitfall of pantsing is the murky middle. What do you want happening to get your characters from Point A to Point B? It's a hard question to answer, and without a little planning you can really get stuck. Another pitfall is the amount of editing you have to do after submission to make your novel publishing ready. The time you spend editing is probably the same amount a plotter takes to plan their story!
Either way both of these methods have good points, and bad points. A good mix of both will lead you to whatever you find to be the perfect method of writing. A writing style isn't uniform, and should be just as unique as the person using it. So all we can say here at eTreasures is good luck, and may your writing process be filled with tears, laughs, and progress!