This game, wow. I really want to like it, but it's flawed on so many levels. I'm up to mission 17 or 18 in the campaign, upgraded the ship a little by now, but I really just don't enjoy playing it.
There's a myriad of patch-able issues like mission bugs, poor and unresponsive UI, supremely inane conversations, pointless first-person-mode busywork, terrible performance, having to be within 100m to interact with any station... I won't go on, people have listed the many surface flaws of this game elsewhere.
The game underneath is just as broken though. On the most basic level, you fly a ship in a 3D world and you can only ever see a 60 degree cone of it in front of you. No real map, no radar, not even a rear view. It's literally incredible that anyone thought this was a good idea, you fly as though a blinkered horse. Combat can be fun in moments but it's marred by this lack of crucial information.
The game universe is actually a decent size, there must be 80-90 different zones (4 systems each with 3-4 sectors each with 4-10 zones each). Visually they have some variation and look pretty nice. When it comes to interacting with them though, it's the same every time. Same station internals, same "personalities", same goods. It's a universe of blandness in terms of interactions.
When it comes to building an empire the same narrow possibilities are revealed again. You can own trade ships, but your options are have them do nothing at all, babysit their every transaction by physically going there yourself, or assign them to automatically sell goods from your own stations. Station building is the one area I haven't explored yet. My understanding is once you build a station you assign a manager NPC and it pretty much runs itself. You can let the manager control some of your trade ships to buy supplies and sell goods.
I'm just amazed that a company with over a decade of experience can so fundamentally misunderstand the genre. You fly without any ability to see what's around you, you explore without experiencing anything new but visual flavour, trading either requires no input at all or your absolute attention with nothing inbetween, oh and if you try to build a combat fleet they can either do nothing at all or follow you around. This game seems to be defined by a lack of information, lack of feedback, lack of degrees of control, and a lack of depth and diversity in general.
I'm not really a hardcore sim guy, though I have played the previous games by egosoft. I picked up X:BTF, X2 and X3:Reunion back in the day, but I only put about 10-20 hours at most into each. I always got the sense those games had real depth, although I found it hard to get past the interfaces and the way the world was presented, and would eventually give up. With Rebirth I just don't get the impression there's anything richer hidden in the gameplay, waiting to be understood and unlocked.
Like others have recommended, X3TC or X3AP are far better at offering the same kind of gameplay as Rebirth, and a whole lot more as well. X3TC was the first egosoft game I really got into. Oddly enough it wasn't by actually playing the game, since all the real depth still seemed hidden behind all the esoteric systems and complex UI like in the previous games.
Instead I happened to come across some dude's playthrough, that amazingly, shone a light on the possibilities of the game just so much better than the manual or the woeful in-game plots. I've always found the concept of fan-fiction pretty laughable (no offense to fan fiction types!), but this is more like a captain's log of the guy's playthrough, a lets-play before youtube took off and with much more brevity (and humour). I highly recommend reading through the first few pages at least -
http://www.egosoft.com/download/x3tc/files/SquiddyVol1.pdf. By the time I finished reading it, X3TC sounded like the most insanely fun game to get into and I better understood how to play it.