The Empress is a cold water dive. Expect water temperatures in the 34F to 40F range.
It is not a very deep dive. The port side rail is at 85 feet and the bottom is ~140 feet.
There is current. The Empress is in a river! This current varies. Tides are a significant factor. However the 10 knot claim can only be viewed as BS.
It is dark. Not a lot of natural light makes it through the water column.
Visibility is low. Less than 10 feet is possible.
The Empress is large. Its something like 550 feet long and 55 wide and 10 decks tall.
Several of the upper decks have collapsed. There is still a great deal of penetration that can be done.
You can do easy penetrations or very, very difficult ones.
The combination of all these factors can make the Empress a challenge if you don't have experience diving in dark, cold, moving water with low vis.
However, keep in mind that to local divers who don't penetrate the wreck or do deco, the Empress is just an AoW dive. This fact was pointed out by Kim Martin who has made documentaries on the Empress.
Kevin McMurray's book is fairly good. However I found that he used too much hyperbole when I compared his writing to my actual experience diving on her.
