Each ship is well described, brilliantly illustrated with cutaway diagrams and detailed labelled pictures of all the main parts.
The history of each ship is then described and various parts of the ship will have a more in-depth write up.
The original NCC-1701 (original series) and Enterprise-D (from The Next Generation) seems to get the lion's share of the book compared to the others. Not an issue by itself, but would have been good to see the others get a bit more detail.
If it's just Enterprise-D you want to know about then [b:Star Trek The Next Generation: Technical Manual|3926173|Star Trek The Next Generation Technical Manual|Rick Sternbach|https://images.gr-assets.com/books/1348266982s/3926173.jpg|141022] is a lot more detailed.
Along the way there are also looks at parallel universes and how transporters work.