Hmmm... It's more their kind of middle period that's generally considered more difficult. If you haven't heard it, you might really like their first record Incunabula, it's not totally different from Oversteps. I'd say it might be their most 'listenable'/friendly sounding stuff. Was thinking that I may have seen Warp reissue that on vinyl recently, but a quick check tells me that I may have dreamed that or something. Anyway, they didn't really go off the deep end musically until Confield.
Then again, their new one is over 2 hours of music, so if you like it that might be enough of them for a while. It sounds kind of like a bit of everything from their entire career, all in one collection. I like it a ton so far, only having heard it twice (it's very long). This album coming out has gotten me listening to lots of their stuff again.