Model.wise, this loco is spot on. Textures and animations are beautifully made as well. However, I have some things to say about sounds, particles and the performance.
First of all, the sounds. The chuff sounds are far too quiet. They sounds like the small chuff of a British tank engine, not the booming exhaust of a mighty 2-8-0. Adding to this, it is mostly overshadowed by the constantly blowing safety vave (I will touch on this later) and the horrendously loud flange squealing/rail grinding idk how this is called. I feel like if the chuff sounds would be replaced by the one on the Brooks Mastodon, it would be a huge difference.
Now to the particles. The main exhaust is just a steady stream of particles/steam, no individual chuffs, just a steady stream, even when the loco is idle. They made perfect exhaust particles for the Brooks Mastodon, and I don't get why they didn't do it on this one.
My last point is the performance. The loco behaves like a race car. It hauls a loaded 12 car passenger train up a 1.5% grade with only 30% regulator and maybe 40% cutoff and accelerates from a standstill to 30mph in a matter of about 1 minute. Also, if you fire correctly, have the regulator open for most of the time, and the dampers open, the safety valve can't keep up with letting excess steam go and you will reach 250psi boiler pressure (The loco was built for 210psi).
Overall score: 6/10: I could look over the performance if sounds and particles were up to MR standards, but sadly they aren't. I hope there is a fan fix soon, or if MAchineRail will make another update which I highly doubt. Anyways, if you like the loco as it is currently, go buy it, but I will certainly be spending a lot of time in RWTools correcting the loco to my liking.