I liked The Truth a lot more on first reading than the half-dozen or so books before it, which were what I tend to think of as Pratchett's Difficult Middle Period, when he is feeling his way from parody to satire. I liked all of those a lot on re-reading, because having read the later ones I could see what he was trying to do, but everything from Jingo to The Fifth Elephant left me cold first time round. I think the tone shift in The Truth was where it started working for me again.

William is an interestingly complex character, and definitely not presented as being as right as he thinks he is - there's a lovely scene where he's talking to Goodmountain and having his tolerant-liberal-white-boy ideas about dwarf culture smashed to smithereens by a conversation with an actual dwarf, which really stood out for me this time round, because it's all about having to talk to people and understand their culture, not just tolerate their differences, and that seems like a really important message.