ActiveCampaign is the core of my business. It's used to store customer/prospect data, email customers and prospects, track website behavior, and provide analytics. It addresses the problem of wanting the power of modern marketing automation, but not wanting to pay thousands of dollars per month.
Ease-of-use. Marketing automation has never been this easy. You don't need a marketing tech background to build elaborate automations in this tool. Everything is intuitive.
The automation builder is flat out incredible. For an inexpensive solution, I'm blown away by the automation capabilities of ActiveCampaign. It blows many of the more expensive solutions like Pardot out of the universe. Not quite on a Marketo level, but ballpark.
Affordable. The thing I love about ActiveCampaign is that it's inexpensive to get started, but won't restrict growth. AC scales from start up to enterprise.
No landing page builder. Having to integrate a separate tool for landing pages is a complexity. On the other hand, I respect that they stick to their strengths.
The reporting is hit or miss. Some of the reporting (example: email open, click through, etc, analytics) is exceptional. Some, like connecting form fill outs to emails and automations isn't quite as clean as I would like. It's workable.
I wish the user interface of the CRM was configurable. Being able to create my own contact layout would be nice.
ActiveCampaign is more modern than most other solutions. The ease-of-use is on another playing field entirely. The automation builder is a marketers dream. Downfalls are the lack of landing page builder and general necessity of integrating through Zapier, not native.
If you're looking for affordable, easy-to-use marketing automation, it's hard to beat ActiveCampaign. One of the very best solutions if you're not flush with cash and able to drop 80K on Marketo. If you're a complex organization with cash, you may want to look towards a Marketo or Hubspot, as they certainly have more functionality. With that said, most marketing departments buy more than they need.