I didn't like them on Later, it all seemed just too formulaic to me, "Machine Gun" was just one drum loop with a little bit of singing over it, nothing outstanding. the other ones they did just left me cold.
I will admit I am a huge Portishead fan, but they will have to really really go some to beat "Mysterons" for me I'm afraid.
Oh and on the subject of it being called Third, they have only ever released two albums of original material, the "third2 album was a recording they made with NTC Phil, and that only contained songs from their first two albums! Hence Third is the 3rd studio album.