The short answer: Yes! WordPress is good for SEO.
However, like any other tool it can be used properly or it can be misused. A decent WordPress blog with unique content that is categorized logically and tagged appropriately is a very good CMS to use for SEO purposes. Of course, there are a few places where “out of the box” WordPress does have some shortfalls.
First, with the standard WP installation, there is no way to control the Title tag and meta description. Both of these elements are important to SEO. To take control over these two items (and a whole lot more) you’ll need a plugin (or plugins). I like both Yoast and “All in one SEO pack” for this. Both of these plugins do essentially the same thing, they give you more control over how the search engines see your posts and pages. Incidentally, both of these plugins have free and paid levels. The Free versions of either of these plugins will be good enough for most installations.
While WordPress is an excellent platform, site structure is a concern. Now, don’t get me wrong, it’s not that WP sites are structured poorly, it’s that too often inexperienced site owners don’t pay enough attention to how they structure their content. When writing your posts and pages it’s easy to try too hard, like adding too many categories and sub categories to your posts. Doing so has the tendency to water down your sites theme. Search engines like clear focused websites, so they can “understand” what they are about. When each of your posts is associated with ten different categories, the engines get confused.
A more SEO friendly site structure is called a “Silo”. With a Silo structure, you are organizing your content in a very tight and specific way, you section off your content into different categories (or Silos). So, a site about “Widgets” may have separate silos for: “Blue Widgets”, “Red Widgets”, “Green Widgets” etc.. Under the “Blue Widgets” Silo you will have a number of posts/pages all about “Blue Widgets” that are linked in a chain. So the top level “Blue Widgets” page will link to the first post about Blue Widgets, that post in turn will link to another post also about Blue Widgets. All of the “Blue Widgets” posts will link back to he main “Blue Widgets” Silo page. A Blue Widget post would never link to a “Red Widget” post, that would corrupt the Silo. While Silos are very effective for SEO purposes, they are difficult to maintain in a standard WordPress website. To correctly “Silo” your site, you really have to forgo the standard WordPress navigation system and develop your own.
One more consideration, regardless of what platform you use (WordPress or some other CMS), content is always king. That means, just having a WP site is not guarantee of SEO success. You have to create compelling content that is related to your niche. You have to do that consistently to show the search engines that your site is growing. If you do that then your choice of CMS or site structure becomes much less important. That’s the real SEO trick!