So I went out and bought Rule the Waves 2 based upon this thread. I have spent pretty much the last 3 weeks playing it, so I'd say it's worth the price.
The game has some odd mechanics, and after a few playthroughs you start to realize that capturing more territory doesn't really enhance your empire's power in the way it does in most games. However, the ability to design your own ships is the real draw here. This is particularly a challenge in a 1900 start, when the post-ironclad ships and technologies you start out with are hilariously bad. As in, you probably won't be reliably hitting anything unless you're at point blank range. Just like real history!
But then, surprise surprise, ship designs start taking on a much more modern form by 1915 or so. By the mid 1930's, you're designing carriers and warships that look like they would be at home in World War II. Again... just like real history!
The bigger the ship, the longer it takes to construct. A destroyer might take around a year to build, while a modestly-sized battleship or carrier will probably take over two years to construct. As a consequence, your newly constructed ships are always *slightly* technologically outdated. Ship refits can be a temporary band-aid to this problem, but eventually, core technologies will have advanced so far that an old ship will no longer be competitive even with a comprehensive refit.
For example, as Austria-Hungary I designed a class of coastal battleships featuring four 16-inch guns mounted in two forward-facing turrets. Fifteen years later, I was able to replace these ships with a class that featured eight 16-inch guns in two forward facing-turrets (four guns per turret). Despite being superior to their predecessors in every way- speed, armor, firepower, fire control, secondary weapons, AA defense, all of it- these newer ships weighed nearly 2,000 tons less, and were less costly to maintain too. The issue? They each took around 27 months to construct, and during that time I was highly, highly vulnerable. Keeping your fleet tightly modernized AND reasonably sized without going bankrupt are core challenges of the game.
To a warship nerd like me, this is great stuff. My only complaint is that the limited variety of in-game events become a bit dry after a few playthroughs.