I have never read Aeschylus before. I was familiar with some of the basics of Greek mythology and I've read some of Homer and Sophocles but that was about it. I wasn't sure what to expect, but I enjoyed these plays, with the exception of The Suppliants, which I thought was too slow and a bit boring. I liked Vellacott's translation. I can't comment on the accuracy of it, but I do think he did a good job bringing the plays to life. Once I got into the plays themselves, I could sense a rhythm for each one and made it pretty easy and fun to read. His introduction is short-a brief note about the playwright and then some background information on the plays themselves-a brief synopsis and the main themes of the plays. He doesn't overwhelm you with background information in the introduction. There are a few pages of footnotes. They weren't overly footnoted, which I liked because they didn't break the flow of the dialog.
If you have no knowledge of Greek mythology, I'd suggest some brief background reading before diving into the plays to familiarize yourself with some of the main players in the plays. Worth checking out for sure.