Rule the Waves 3 just like its predecessors combines the AAA graphics of Windows 2000 with the learning curve of arch linux.

If you are a new player, you have to ask yourself some questions before buying:
1: Do I need fancy graphics?
If the answer is yes - this obviously isn't your game. However it has to be noted that the ship models genuinely look a lot better and more detailed than in older games (still in the same style though).

2: Am I allergic to reading?
If the answer is yes - not your game. RTFM is probably the best advice I can give to new players. It's well written and explains a lot of the deeper systems of the game in a way that makes sense. You will also do a ton of reading in game.

3. What constitutes a good UI to me?
Okay, this one is a bit more difficult. As a developer myself, I *love* the UI in this game. It is simple but extremely effective and allows you to do everything you want *quickly*. There are also hotkeys for all sorts of actions. I much prefer this to the bloated and unresponsive UIs of other games in the same niche (looking at you, UaD).
But yeah, it looks like Excel.

4. Can I accept losing?
In this game, especially if you are new but also later on, there will be situations where you will get beaten by the AI. Sometimes you made a mistake, sometimes there really wasn't anything you could do. Once torpedo ranges grow and especially when carriers enter the mix, sometimes your enemy will get lucky and you won't.
Alternatively, the leader(s) of your nations may make stupid decisions that make your job a lot harder.
You are playing as the head of the navy, you are not in control of everything. If you can accept that and want like to play a role Rule the Waves will be great for you.

5. Do I like to micromanage?
If you do - this is your game. If you don't - good news! In RtW3 some of the systems can be automated a lot better than in older ediions. You will still have to manage a lot of things though, don't worry.

If you enjoyed the older iterations of this franchise, this one won't disappoint you too. For players of the old parts the new tech and additional systems that allow for even more micromanagement are probably the main selling points.

Making promises for the future is of course always a tricky thing with game releases but I do want to add that NWS have a *very* good track record when it comes to maintaining their games. Rule the Waves received bugfixes and content updates until RtW 3 got announced (I think one final version after that even).
Devs are very active on the forums (which I can recommend you use, lots of great advice there), listen to feedback and are apparently already working on the first update.

The game is also modable, it probably won't be long until the first ones using the new systems come out (some mods for RtW2 are also being converted afaik).

Overall:
Rule the Waves 3 is a great game with a great community. It surely isn't for everyone but if you like these kind of games definitely give it a shot!