What do you like best?
Most "suite of tools" marketing products are in fact focused in just one or two tools or functionalities, all the others being an afterthought.
That's not the case with HubSpot. HubSpot invests heavily in R&D, and is continuously improving the existing tools and launching new ones. They also do a great job of educating marketing professionals not just about how to use the software, but also about strategy, concepts and best pratices.
What do you dislike?
I do think the HubSpot CMS has a long way to go before it's as easy to use as it should be. It still requires quite a bit of technical knowledge, and for non-coders, the learning curve is steep.
Recommendations to others considering the product
From a marketer's perspective, technology should be always seen as a means to an end. Specifically, to support whatever strategy you ALREADY have in place that needs implementation.
I've seen it time and again: marketers who think that purchasing some fancy tools pretty much guarantees the success of their projects. It does not. If you START with the technology, quite simply, you're doing it wrong.
If you have no idea what your actual business goals are (sales, revenue, growth, etc.), or who your prospective buyers are, you should fix these problems first. Invest the time and effort to create a strategy that is coherent with your business goals and your audience.
What business problems are you solving with the product? What benefits have you realized?
I have implemented marketing strategies in 50+ companies relying heavily on HubSpot as a tool. The business goals tipically are generating demand (increasing traffic), increase conversion rates along the sales funnel and, most importantly, improving the overall buyer/customer experience as a way to shoten sales cycles, increase the perception of value towards the product/service and anything else that might help accomplish the ultimate goals of bringing down the cost of customer acquisition and increase customer lifetime value.