The thing which bothers me -- apart from the usual widespread concerns -- is that we're on the verge of 'road trains' being feasible as almost totally automated transport. My gut instinct, as a lifelong non-driver and public transport user who's spent a lot of time and money on trains over the years, is that it's a very difficult time to be buying flagship infrastructure.
By all means improve some of the embarrassingly poor, slow cross country connections, but in another decade we might be looking at electric 'bus trains' for mass transit at affordable (rather than HS2 premium) prices. I think that will take a lot of capacity off many rail routes, because there are a lot of us out here that like the speed of the train, but struggle to justify the cost (unless you can plan three months ahead).
The west coast routes can be expensive and very crowded, especially if you have to travel on the first 'cheap' services, but I have no confidence whatsoever that HS2 will do anything to solve that. It gives us a seat at the "big boys' train set" table, but it's beginning to feel like yesterday's solution. To me anyway.