I'm interested in what people like most and least about the databases they use. For instance, I mostly use Oracle at work, and about the only thing I like about it is that it's easily supported by other software packages that need a database of some sort. Aside from that, it's resource hungry and has a lousy command line client. In projects where I have my choice, I use PostgreSQL. I know my way around PostgreSQL better than I know any other database, and I can get stuff done when I'm using PostgreSQL. I can (often) easily see why slow queries are slow and what to do about it, and it supports complex SQL. I don't like upgrading it, and although I don't mind that a default PostgreSQL installation doesn't come with a kitchen sink full of add-ons and modules that I'll never use, when I need a module it's occasionally tough to find what I need and to make it work with the installation I've just done.
What do you like about your DBMSs? What do you dislike?