Watch them. The new season begins September 25. There are only 12 episodes in season one so getting through them in the next two weeks shouldn't be too hard. The DVDs contain a bunch of special features, including an unaired pilot and an unaired 13th episode, but you can skip the unaired episodes. The original pilot was chopped up and incorporated into the first four aired eps, and ep 13 was never intended to air so the producers got a little wild with it. Neither one fits into the arc of the stories so if you're pressed for time, just watch the 12 aired episodes.
Since I've convinced you to watch the DVDs, I will give you only the briefest of primers. Dollhouse is a serial. Although there are individual stories each week and one-time-only characters, part of each episode is used to push the series to the twelfth episode. The tension will build - trust me - until the final episode when all threads of the season come together for a heart-stopping finish. The premise sounds simple - a company rents out people with customized personalities to order. When they're not out on engagements, the "dolls" have their memories wiped clean. They become blank slates.
There are a lot of characters at first. Echo is the main one - she'll be easy to keep track of. Boyd is her handler. He's kind of like us - the external viewer, a skeptical outsider. Miss Dewitt runs the place and is as complicated as as a doll is simple - it will take a few episodes to get the hang of her character. Paul the FBI guy is the relentless pursuer. Keep an eye on him - he is the force that drives much of the ongoing activity in each of the episodes. The rest of them - the other dolls, the tech guy, the security chief, the neighbor, the doctor with scars will all come into focus after 4-5 episodes.
It will be a little odd at first to identify with a character who has no personality - in this case, wiped after each engagement, but Dollhouse is not the first show on TV to use personality-free characters. Think of Mission: Impossible where you never saw any of the spies outside of a mission. We knew nothing about them personally; they were on screen only to perform the mission and get out. How about the first few seasons of CSI? The characters had only the most perfunctory personalities. They existed only to investigate the crime scene or run lab tests. In Dollhouse, it's a little more complex, but a doll's initial function is to be imprinted with other people's personalities in order to do an engagement. The stories get good usually when something goes wrong.
If you read this post because you intend to watch season one, DO NOT READ THE POSTS BELOW. THEY CONTAIN SPOILERS. Big spoilers.