I tried almost all apps for basecamp. Including outpost and insight. And i must tell you that 21st is exciting age to live! You can get something for free which is better than non-free alternative, or at least on par. Sherpa allows you to do something what outpost and insight do not allow: 1) post messages to people 2) call ppl from inside the app 3) create milestones I give 4 stars but not 5 now because I want to see: 1) more stability 2) iPad version