Ditto, Maria. I rented the first six episodes, and have watched both Serenity (the true first episode) and The Train Job. And I've gotta say I'm blown away. I was pretty hyped up after reading all the glowing opinions of the series, and it still managed to surprise me with its quality.
The script is fantastic. When Joss Whedon wants to write good dialoge, she writes REALLY good dialogue, and that's all there is in this series so far. Love some of the jargon she created too. I also love the characterization. I was amazed at how much I already cared about all the characters just an hour into Serenity. The plot, while not entirely original, is quite compelling. The acting is top notch, helping me to completely buy into both the characters and the plot. The universe that Whedon has created is quite fascinating. I love the diverse cultural influences; the stark contrast between the "clean and brand spankin' new" technology of the Alliance at one end, the primitive technology of the border worlds, and the technology of our heroes (and anti-heroes) somewhere in between; and I love the "western-in-space" feel. Oh, and above all, I love the very different (for sci-fi) yet strangely appropriate soundtrack.
I think I like it more than Star Wars, and that's saying a hell of a lot (not to mention taking me completely by surprise)!
My wife typically hates every sci-fi TV series that comes out, but after I watched the first episode by myself, I made her sit down with me while I watched it a second time. Now she's hooked, too.
I don't know if Whedon has commented on it, but is the reason that the only languages used are English and Chinese related to the idea that America and China may become competing superpowers at some point, and that as a result only they had successful space programs and were able to populate the stars? Or is it just because she likes Chinese?