Peerio is especially useful for sharing large files – something that is often difficult via email or requires using insecure services like Dropbox. It also has group chat functionality and it is – compared to alternatives like PGP and OTR – very easy to use for computer novices. It works, however, only with an account on Peerio’s central server and thus potentially leaks meta-data (and makes you depend on a commercial entity). It is also less established than PGP and OTR and its security promises should therefore be treated skeptically, especially as most users will not be able to check updates for correspondence with the source code. It allows one to have much more private conversations than most other popular apps, though, and therefore might be a good compromise to use for communications with people who do not have the skills and time for more advanced solutions.
If you’re interested in using Peerio, my user name is
tstahl and my cryptographic identity (a so-called “MiniLock key”) is
D4wYAnKrcrEXWu7tZdpV8mULB8fvNguYymHu3Z6GjMDjN. If you use this referral link, you also get 250MB extra storage space.