This game looks really interesting but I bought a similar game (Star Wolves) and I found it very disappointing (Problems with the movement of ships, their AI etc). Also the lack of games of this genre makes me a little suspicious... Has anyone tried this one? Was it any good?

I really liked it back when I played it. The combat is very tactical, with emphasis on disabling specific systems on your opponent's ship. Every gun on your ship can be controlled individually, and energy management is very important. Later in the game when you control around 5 ships, it gets micromanagement heavy. If thats not a problem you'll get a fine feeling of controlling a powerful, complex war machine, not a unit. Less Jean-Luc Picard firing the standard barrage of weapons and more like Jeffrey Sinclair of Babylon 5 redirecting individual batteries because there's a nice target of opportunity on the other side of the ship.
Obviously this is not a objective opinion, I loved this game. The flaws I can remember are some missions that were enervating, especially he stealth mission. Some of the voice work will make tour ears bleed. And I ran this on a crappy machine back then, so I had frame rate issues, don't know how this runs on a modern machine. Speaking of visuals, this is the only game that gets that space is dark, when on the shadow of a planet or asteroid you'll only see the lights of yours and the enemy's ships. Amazing.
For this price is a must buy for me, but I was ok with spending half the time in the game on pause commanding every piece of my ships. Hope this helps.

That really helped me! I enjoy hard games and that kind of micro-management so I'll give it a try. I specially like the fact that you can pause game to give orders because that is a great addition to any tactical game (I love the Dragon Age combat system in which you are constantly pausing the game to change orders).

Thanks for your answer!

P.S: I really like your avatar, Hellsing is one of my favourite animes

Might be a bit OT but: Have you tried the older Bioware RPGs yet? They feature comparable gameplay and require much tactical thinking (at least most of the time).
Baldur's Gate 1 & 2
Nevewinter Nights
Star Wars Knights of the Old Rpeublic

I've never tried Baldur's Gate or Neverwinter Nights because I'm not too much into D&D's stuff (I'm more of a cyberpunk fan). I wanted to give a try to KOTOR but I never got around it. Anyway I'll take a look at Baldur's Gate and Neverwinter because I loved the DA combat system!

Icewind dale has better combat (and atmosphere) than baldurs gate.

If that's more important than story/exploration you could take a look at those?

I dont get it. I couldnt get the demo through at all. It seems to be a very complex game... Or I get something wrong;)

The demo for Nexus is pretty hard indeed, considering the lack of a tutorial and that they throw a whole fleet at you at once. The actual game introduces you nicely to all the game mechanics step-by-step and you control only a single ship for the first few missions...

So don't be put off by the difficulty of the demo - the full version makes it faaaaar easier to get into the game.

Thank you, maybe I will get it on the next sale...

I again got completely frustrated about how difficult and specific some of the missions are in the game.
Every few missions the game just throws you a task that requires near-perfect execution, and I just cannot learn the patterns without hours of failing and grinding my teeth. It's enough to completely ruin my enjoyment in the game to see an objective fail in seconds because I didn't nail down some specific detail just right.

The game is good when it's not demanding perfection from you.

Well, if you want to use a walkthrough, i found some links:

http://www.gamefaqs.com/pc/525559-nexus-the-jupiter-incident/faqs/40842
http://www.gamefaqs.com/pc/525559-nexus-the-jupiter-incident/faqs/33589
http://www.gamefaqs.com/pc/525559-nexus-the-jupiter-incident/faqs/33476

Be aware, this guides can contain some spoilers.

I think I've gotten used to too much freedom in my space sims. But I do know that I'm moving onto other games for a while. I need to let my nerves cool off.