Buffer is easy to use, and best of all they provide killer content on their blog offering everything you need to totally crush your social media and content marketing. The free version isn't anything fancy, but it's easy to use and covers what you need. Additional plans aren't super expensive, but they also aren't as comprehensive as other tools.
Analytics for paid plans show best and worst performing posts based on engagement (for retweets, favorites, replies, likes, comments, clicks, reach, and post type).You can also export for easier analysis, for reporting, for additional review, etc.
Buffer is extremely straightforward, but provides less bang for your buck compared to bigger tools like Hootsuite.
It also contains an automatic link shortener which "Buffer-brands" all your links, which is a bit annoying.
Analytics on the free version are limited and the lack of monitoring tools likely means you'll need to add a second tool to your repertoire. The free version also makes it difficult to recycle posts, which can be frustrating.
Really the bottom line is that Buffer — even a paid version — isn't comprehensive enough for a super serious marketer or large team. It would likely need to be combined with other tools, which can be cumbersome.
Free version is great for simple/limited scheduling across platforms.
The free version is pretty solid if your social budget is zilch. You just can't schedule more than 10 posts per platform.