Pratchett disappoints

Terry Pratchett has always been a hit-or-miss writer for me. This one was a clear miss. I expected so much from it. I enjoyed the two previous novels about Moist von Lipwig – Going Postal and Making Money – but this book didn’t even come close.
It has two interlocking story lines. One – the arrival of steam power on Discworld and the building of trains and railways. Two – the dwarves’ resistance to the advent of progress, both technical and social. Some of the old-fashioned dwarves want to return to the good old days, when dwarves had nothing to do with humans or trolls. The proponents of such a regime call themselves grags and embark on the campaign of terror and subversion to drive their point home.
It sounds interesting, but the writing is bad. The novel includes so many points of view, I lost count. It doesn’t read like a coherent story. It reads like a collection of the writer’s notes of what should be / might be considered to develop this novel. There are dozens of short interludes that demonstrate the main concepts of the story. Most of those interludes are tiny scenes, populated by characters that appear only once or twice in the entire book. They don’t propel the plot. They don’t develop the main characters. They do nothing.
As a result, the story lacks focus. It’s disheveled, unstructured. It also lacks the protagonist. Everyone comes and goes across the pages, most of them the characters I know and love from the previous novels of the series, but I couldn’t figure out whose story it is. All the participants seem cartoonish, interchangeable. Only the names are different.
There are some highly quotable lines scattered here and there through the text, and the author’s acerbic observations shine, as ever, but other than that, this wasn’t a memorable book. In fact, it was very disappointing. Maybe the author’s developing Alzheimer was to blame for it?