Unless your business relies on it, or you have other software that plugs into Basecamp, there’s no reason to stick with Basecamp.
Basecamp is very minimalistic and is lacking features many teams need to actually get work done. If you don’t need Basecamp, try one of the many open source and free alternatives.
I’ve personally used Basecamp, it’s not great. One of my annoyances is that you can’t assign a task to more than one person. Administration is also horribly set up, as you can only have a regular user or an admin of EVERY project for the account, no mid-level permissioning. Basecamp also isn’t self-hosted, so it goes down sometimes and there’s nothing you can do about it.
I’ve recently come across a few sites with links to some good Basecamp alternatives that I’ll try out the next time I need a project management tool.
Collabtive – Free Open Source Basecamp Alternative
WebCollab – Free Open Source Basecamp Alternaive
Freedcamp – Nice name. :P
GoPlan – Paid Basecamp Alternative
Comprehensive, Sorted list of Basecamp Alternatives
More Alternatives to Basecamp via AlternativeTo.net
What’s your favorite alternative to Basecamp?
Update 11/30: Basil in the comments suggested ProofHub. I hadn’t seen this alternative before, but the Google Apps integration is the first I’ve seen across these alternatives. I know stock Basecamp doesn’t have that, and it makes it a great alternative for the Google Apps users out there.