I love the simplicity of having all my data organized so easily, no matter how many different platforms I have used on other projects. It's also nice that you can pick different email lists to send to depending on which product you are testing. However, not every list will support "Unsubscribe" functionality correctly for each platform. For example, if someone signs up for one newsletter but then doesn't receive it because it got auto-triggered with their first product, they may be upset about the unsub even though there isn't an actionable way to un-unsubscribe them from that channel. I'm working on a program that tests different email channels across multiple devices in one place. Effective Experiments allows me to keep track of everyone who signs up for each version while at the same time keeping track of everyone who does or doesn't open emails related to each campaign. I like that it's easy to create workflows, track tasks, and view results in one place! The UI could be more intuitive - there are some features where you have to click through multiple pages before getting what you need or even knowing something exists. We use Experiments daily as part of our data collection process. It makes keeping everything organized much easier than if we had used Excel spreadsheets.