Don't ship something that's not ready. If you have a subset of the product that makes sense to release, release it, but most likely releasing a subset that's not designed to be used standalone will leave you with a product that has some glaring holes and inconsistencies.
If it's going to have bugs, frustrate customers, or worse yet, lose their data, sit tight and polish it until it's ready. If people are waiting for it, send them a clear update saying that you know that they are waiting, that you are working on the final updates, and that you expect it to be ready at such and such date. Your customers will appreciate the transparency, and won't mind waiting a bit longer if it means they get a product that's a joy to use.
This doesn't apply if the customers are waiting for a beta release - in that case, go ahead and release, just make sure to remind them that the product is in beta, and therefore bugs are to be expected.