Thank you for your reply , i have some questions : 

well I didnt know about the new sounds and music... so i bet these things are not in the beta ??! cause i've heard the same sounds as always

Nor the textures... I've read some people were sayin that textures for older ships are the same as before.. !?!? Did they really revamp all textures? 

what's new about the UI ? It seems the same to me ?! 

I noticed that stardock sells Rebellion with discount for previus owner and describes it as upgrade. I decided I'll buy it as of now for 20€ .... 

As for the music I really haven't paid attention but there are new sounds.

The textures themselves where not changed but they are cleaner and the new shadowing effect makes things stand out better.

Actually that was the first thing I noticed. Each race (not faction) has its own unique UI border.

No, but they added shadowing, etc.  The UI isn't much different either, just prettier.

But you've missed new factions.  Rebel & Loyalist for each race.  Thus 6 new titans. New tech for each of the 6 factions - so lots of completely new strategy.  Also 3 new Capital ships, and abilities now level up one more level, so new strategy there too.

Even tho its just an 'expansion', IMO it plays like a new game.  Also now has steam support, so multiplayer has exciting potential.  I could go on & on.

[Edit: Wow, I got ninja'd by 3 ppl!]

Indeed, I have been playing Rebellion day and night (well maybe not that much but still a lot). Even though there are small changes, the game feels a lot different to play

where can I find pictures of the vasari GUI ?

Skin_Phase.tga

Its a solid improvement, especially if you didn't have the two micro expansions, though I'm hoping we'll get some more stuff after release. Hopefully soon after release many of the mods will be ported as well, which certainly have many, many things that the Vanilla game didn't have. So yes, between all that it certainly has the potential to be your summer time sink.

Modders can actually afford to put more time into making content than Devs can simply because they don't need to have as strict quality and testing standards. That and the fact that there are many more modders than devs (for Sins anyways) means this is going to be inevitable. No modder could have made ships that looked as good as the titans though, and the new lighting system as I understand was quite revolutionary as most light/shadowing methods were too memory intensive for a game as large as Sins, so even if mods have more content that doesn't mean Rebellion isn't a better product for other reasons.

That and the fact that if memory issues don't hobble some of the biggest mods, all modders will have more flexibility with Rebellion, so by getting Rebellion you'll almost certainly get mods with better content than Diplomacy mods after they transfer.

I dunno.  Titans and corvettes, while only "2 new ships" are complete gamechangers.

Corvettes offer direct counters to some of the most popular strategies in Diplomacy(mass LRM frigates & carrier rushes), and moreover complete the  cycle of early game frigate counters:  LF<LRM<CORVETTE<FLACK<LF.....ect....

Previously it went something more like: LF<LRM<SCOUT- and due to the low general military utility of scouts, most races just countered LRM frigates with their own LRM frigates or massed flak.  Later on the greater availability of fighters smoothed things out a bit.  But the cycle of counters is a lot more natural now with corvettes in.

Titans likewise are a late-game gamechanger.  In some situations large lategame frigate fleets suddenly become a liability as they risk feeding the enemy titan.

other then that rebellion essentially doubles the number of playable factions- sure there are tremendous similarities between the loyals/rebels of a give race- but they have been differentiated enough that they often embrace different tactics and playstyles even if they are using most of the same ships/techs.

Basically, it's Diplomacy with the addition of Titans, Corvettes, and new victory conditions.  If you already own Trinity, the primary reason for purchasing it is online multiplayer PvP ("the real Sins game").  Presumably, most if not almost all of the PvP action will migrate to Rebellion and hopefully hundreds of people will be playing it online at any given time.  In contrast, if you only play single player against the AI, then it might not make sense to purchase it if you already have Diplomacy since you can enhance the game with free mods.

I don't see scenarios listed in the features...

Sins of a Solar Empire: Rebellion contains all of Trinity’s features plus:

• Civil war has erupted within the TEC, Advent and Vasari races; customize your faction and unlock new options by declaring yourself loyalist or rebel.
• Updated graphics bring Sins of a Solar Empire to life as never before, with new particle effects, enhanced textures, and improved shading.
• Six massive Titans enter the fray - each with upgradable special abilities - giving loyalist and rebel factions a way to eliminate their foes.
• Three new capital ships bring immediate options to the table, offering even greater strategic depth; while existing capital ships have been rebalanced for their roles.
• New technologies grant loyalist and rebel factions new ways to advance towards the ultimate victory!
• New corvette class ships use their enhanced speed and maneuverability to weave through the battlefield, inflicting damage to enemy ships’ systems.
• AI enhancements make single-player games more fun and challenging than ever.
• Multiplayer optimizations for Ironclad Online make getting games set up simple.
• New victory conditions provide multiple paths towards becoming emperor of the galaxy.

Thus far, it's easily worth it if you liked Sins before whether you are playing single player or multiplayer.  The new units, techs, and balance changes really breath some new life into the game.  There's a few question marks I still have that I hope will get addressed either by launch, or shortly after:

-AI; it has sucked throughout the beta, but it's slowly getting better.  I'm hoping by launch they have it pounded into something that will be fun to play against.

-Ladder and matchmaking for multiplayer.  This is deal breaker for me for multiplayer.  Eliminating smurfing was a big gain, but we all know how Sins multiplayer went without proper competitive tools.  Not all of us think 4v4 and 5v5 is fun, but I can understand why people went that way with the low player pool (if you're going to host a game with only 10 people online, might as well get all 10 people in the game).  While these omissions were not the only reason Sins multiplayer failed the first time around (bad early balance, trolls, and minidumps played a huge role), hopefully Ironclad does NOT underestimate the importance of this if they want the Sins multiplayer to actually grow this time around.  No 1v1 or 2v2 ladder/matchamaking = no ICO for me once again.

-Pirates; they just don't know what to do with them.  New players hate them because they're too strong early on, experienced players find them too easy to remove if they ever become a problem, and both player bases hate the stupid ebay system and quickly learn to just turn off the pirates.  Ironclad keeps tweaking their strength, but that's never going to really fix them.