The last big change I was excited about would definitely be CrossRail opening. That seems like such an eternity ago now! Absolutely fantastic to have it and it seems incredible how we all got by without it!
Others have mentioned the 745s and 755s, and I too was really impressed by them. I still am, and really want to head over there again.
I remember being very excited about the IETs entering service on GWR, and I fondly remember loving my first experience of one. Well, technically two as I had a pair from Cardiff to Newport. I stand by my view from back then too, I liked them from the start and I still like a journey on an IET.
Something else I was pleasantly surprised by was liking my first 385 experience in 2020. They are pretty decent little trains, and I've just put myself in the mood for a Scottish adventure! Similarly, way back in 2011, I didn't think I'd enjoy the 380s and I remember joking somewhere on the forum that I didn't want to point my camera at one, for fear of the camera breaking! Cue a journey on one and actually finding them pretty decent trains!
Same sort of thing for the rebuild at Glasgow Queen Street, I had my nostalgia for that station from my first visit way back in 2004, but the new station was brilliant! Birmingham New Street's rebuild, or at the least the concourse level, was pretty exciting and I remember making a special trip at the time to see it. Like Glasgow Queen Street, I had my nostalgia but the new station is so much better.
I think that's all the main things I can remember being excited about, oh wait no, no I've forgot to mention the Class 196 introduction. I first had one in January 2023, from Shrewsbury to Shifnal, and I had high hopes for the train that was to replace the 170s. I really enjoyed my first 196, and I still like them now. They're great trains, not without their faults like most things, but in my opinion they're a great successor to the 170s.
I was excited about the 374s as well, until I did London to Amsterdam and back on two pairs of 374 half-sets. I wasn't overly blown away, as my trip report from January 2023 revealed.
197s, I enjoyed my first few journeys but the dodgy AC on some recent journeys has darkened my opinion since then.
In terms of changes to come on the railway, I have big expectations of the 730s. Much further into the future, I'm expecting many good things from HS2.