Open Office is an Open Source tool. You can view the worklist (the current planned changes), view the QA web site, and download the source code for Open Office from http://openoffice.org
I've never found a problem with Open Office that I couldn't work around. There are some limitations, but both the QA team and the support team are very open about the limitations, work arounds, etc. Some of the limitations are by design, intended to keep people from hurting themselves (or others).
Base can manage hundreds of thousands of rows on its own, and it can use MySQL for "heavy lifting" when you get beyond the scope of what Base can do on its own. This is WAY beyond the scope of what you've described so far. In general, bugs and security flaws rarely live long in an Open Source environment. While you might find a bug, I'd bet that it won't be around long.
I don't have any problem dealing with Base. Different people have different skill sets and different expectations, but I'd bet that you'll find it easier than MS-Access because the design is "purer" because there aren't as many conflicts caused by the need to support many other products.
It's a very different environment than MS-Access both from the perspective of the software package and the community that surrounds it. The things you know about Access may help or hinder you with Base because it is a different product, with a different heritage, and a vastly different support and service model.
-PatP