Empress of the Deep probably was a good HOG at some point, but it didn't age well. If you really like the genre, you may give this a try. If not, look elsewhere.
I was torn whether to recommend it or not, but I feel it's just about good enough if you get it very cheap (i.e. at a huge discount).
The game in detail:
# It has only one game mode. It's fairly easy, and the hint button recharges quickly. There's a random clicking penalty, that doesn't really do much (your cursor moves around wildly for a bit).
# The graphics aren't good. The HO scenes are blurry, and sometimes, the objects are very difficult to be spotted. Awkwardly, most screens have only one item lying around (usually in plain sight), and once you pick it up, the screen is finished. It felt like a great waste of potential to me.
# There are a few mini-games but nothing extraordinary.
# You'll spend a good deal of time backtracking. There's a map, but it's pretty useless. You can't use it to "teleport", and it doesn't indicate the unfinished screens. Thus, the backtracking gets pretty annoying.
# It's quite short. It took me just 1.5 hours to finish it, and I read all the dialogues, watched all the cutscenes, and played all minigames.
# The game doesn't have achievements, but for some reason, you collect flowers. They seemed very out of place to me, didn't do anything, and were impossible to miss.
# The story is somewhat decent, but you can tell the big twist right from when the characters are introduced.
# The voice overs and music are all right.