As someone who's done a great deal of cold email outreach campaigns on a plethora of platforms, Reply.io's modern and slick UI is it's biggest asset. That, alongside the many settings that are given enable marketers to leave nothing up to chance. Everything can be tested (with their native A/B testing tool) and improved upon.
Also, the continous improvements from the developers are great to see. I've been using it for roughly 4-months, and have seen 3 major updates and feature implementations... really good to know these guys have a product roadmap planned out!
Tread carefully - pricing is not as it seems. You are limited to 3 email accounts, with $20 added per email account per month afterwords. This is not mentioned on the pricing page, now the terms and conditions. The unlimited tier is NOT unlimited.
Sometimes the site loads very slowly, or clicking on a certain tab/button will not work. This is likely a Chrome Desktop issue, though, since the site loads and works just fine on my mobile (iPhone 6s).
Do your research.
Reply is a fantastic tool, but it might not be the right one for your campaign or budget. Always do your diligence before purchasing software. These guys have pretty fantastic livechat support embedded into the site, so getting a hold of someone shouldn't bee too tough.
-Reports, metrics, and dashboards.
Reply is NOT the only tool that does email automation, but I've used quite a few and I can tell you this is the best and cheapest email tool in it's class.