The HubSpot COS (Content Optimization System) is a very powerful platform for your website. However, it is not suitable for everyone. Here are some of my pros and cons (please note that some of the things are included in the HubSpot marketing platform, but since you need it in order to use the COS they go kind of hand in hand):
 

HubSpot COS pros

• Everything in one place – landing pages, blog, website, emails etc. – all connected to your marketing channels.
• Out-of-the-box mobile-optimized.
• Faster than most CMSes.
• HubSpot’s CDN (Content Delivery Network) is secure.
• Optimized for the modern rules of SEO.
• Smart content (for pro and enterprise level customers). Make your content more relevant to certain segments of visitors with personalization tokens and smart content.
• Content staging – in-app development environment that allows you to redesign or create staged pages, before publishing them to your production site.
• Easy to use. Easy for developers to get started building templates and easy for anyone to edit pages in the inline editor, no programming skills needed.
• SSL(Secure Sockets Layer). SSL basically makes your site more secure. Also, Google now factors SSL into their ranking algorithm. Setting up SSL yourself can be very painful and quite expensive. If you have the HubSpot Website Add-on, you can add SSL to your site with the click of a button.

The list could go on…

HubSpot COS cons

• Price. If you’re a small business with very limited resources it might be a big step to start using HubSpot COS and paying a couple of thousands each year. First you have to buy the marketing software (+onboading), then the website add-on. However, I guarantee you will come out on top if you put in the time and effort.
• Customization is limited. I’ve stumbled upon some problems where I would like to modify the markup for some of the modules, but couldn’t. There’s a very active community on inbound.org that helps out and most problems can be solved with a workaround.
• No database-driven pages and no server-side code (like PHP).