I'm sorry to say but it's starts to get messy when it's used by a team. Darcs suited me fine while worked alone with projects but as others joined we faces serious problems, including loss of data. I gave it up, switched to Mercurial and never ever missed darcs.

Even when used by yourself. Branch a project, build a complicated new feature (e.g. 50 patches), then try to merge.

The exponential merge problem really sucks.

I gave up on darcs awhile ago, but darcs 2 honestly does greatly reduce the merge issues that used to plague it. If you're still on darcs, get the upgrade. You may find you no longer need to move to a new product.

darcs has a very nice interface, but it does not handle binary files (many/large) well.