If you are in any type of sales, and meeting with people, it is a must. If you already know you contact well, it doesn't have as much value for that particular meeting. Also I wish there was a way to not sync internal meetings, as it just provides clutter, and I don't need info on those people.
Datanyze can be a useful tool for understanding your market. You're able to use Datanyze to see how many people are using your technology as well as who is using your competitors. Receiving alerts on who is adding and dropping you vs your competitors is always helpful. It's a tool that can potentially give back as much as you put in.
Datanyze used to give really good data on specific person level. You could then look up prospects using the Chrome extension inside of LinkedIn. This made prospecting extremely easy and very efficient. Unfortunately, this no longer exists and it is much harder to do without their data.
I have found that sometimes the data inside of datanyze is not always current. When reaching out to companies they will mention that they were just testing a tool, not fully using it.
There are really no other places to push the data from Datanyze except for Salesforce. This makes it tough when using other tools or CRMs.
The thing that Charlie does best is it aggregates everything in one place. It allows me to have a one-stop shop, that I can quickly review prior to heading into a meeting. People are usually amazed with the amount of info that Charlie can give you, and it almost always works its way into my sales call.
I've used products like Builtwith and Wappalyzer and neither compare to the level and organization of data within Datanyze. It's much more robust and easy to access. However, it isn't perfect and sometimes needs to be updated, or removed and re-installed simply for it to function