"For Beginners" is a compilation of material from Killing Joke's EMI catalog. I think like any sort of introduction to the band, the faithful (such as myself) will have complaints about what was included, what wasn't, etc., and such arguements are quite honestly difficult. In this case though, there may be a point to those arguments.
It looks as though they were concerned with even distribution-- two songs were pulled from each album on EG (i.e. "Outside the Gate" and earlier), with a third one from "Brighter Than a Thousand Suns", this evenness gets in the way of the track selection-- I think most folks in trying to introduce the band would emphasize their first two records and "Night Time", but regardless of that, teh track selection-- "Primitive" instead of "Wardance" or "Requiem" (I can understand "The Wait" what with Metallica covering it.....), "Butcher" instead of "Unspeakable", "Chapter III" over "Empire Song"... the list can go on.
If you're new to the band, this could be an interesting introduction, but I think I'd recommend getting "Laugh? I Nearly Bought One!" instead, which reaches one album further and has a much superior track selection.
Of course, if you're a collector, there's some reason for this-- the sound quality is much better, there's a few alternate mixes (including the drum obsessed version of "We Have Joy" and a much more in-your-face "Harlequin", though that could be remastering talking), but for anyone else, look elsewhere for an intro.