I'm in the process of building one & it's not something I'd recommend unless you've plenty of model making experience. The quality of components, fittings, etc. is absolutely superb but most of the timber work, being supplied just as raw materials, requires considerable patience & the ability to read (occasionally confusing) plans to produce a convincing model.
I think mine is an early kit &, so far as I'm aware, they've made changes to certain aspects now that I think simplify the construction.
I guess any model where you're relying on the natural wood finish, without the ability to fill over those little mistakes, is inevitably going to be more difficult.... They do look beautiful though & well worth the effort imho.

When I purchased mine they supplied it with a Cheddar Gemini engine & matching boiler - not sure what the options are now though.
I really must get on with it.
Mark