Subversion is in pre-Alpha state, and there are plenty of known bugs (see the Issues page for a complete list). Frankly, you should probably read over all the open issues. But since you're probably not going to do that, we list below some of the ones most likely to annoy you.
Ah, the joys and pains of versioning directories. If you delete a directory, please commit the whole directory, not just one of the (deleted) subtrees. Your working copy will thank you.
See Issue #387 for more details.
When you do see an error, it won't always be clear what the real problem is. Subversion has a system for throwing and catching errors, but as errors are thrown up the callstack, not every routine attaches a coherent error message. The error messages will improve over time.
If you're going to commit a property change made to a directory, you'll need to update that directory first, to bring it to the youngest (head) revision, otherwise Subversion will reject the commit. This rejection is a temporary workaround for a larger issues Issue #463 and Issue #530.
If you want to add or delete entries in a dir -- in a repeated series of commits -- you must update between the commits, or the server will reject your second commit. This is also part of issues Issue #463 and Issue #530.