I'm not scared or anything about that. Yes I don't really like to read about some law in countries like Saudi Arabia (but also not about the law of some "Christian" countries), how some Islamic countries handle their view of "freedom" (especially of speech), about how they handle apostasy in Islam and so on but I already think that most Muslims who live here in Germany are also not very happy about some of that so that they wouldn't support it if they will get more power here.
I'm also not scared about terrorist attacks. Yes maybe it will get worse, maybe there will die more people per year in Europe because of these attacks but it won't be like in Iraq... You also don't see so much of this stuff in Turkey and if at all, the European countries would transform more in a Turkey like country (and not even that since the young Muslims here grew up mixed with a different culture of which they will adopt some stuff)
I also see how some homes of asylum seekers get regularly "attacked" by Christians or how that guy killed the kids in Norway some years ago to know that people of another religion or even atheists aren't better humans, it's probably more a problem of how many chances people had in life, how happy they are and if they turned to be assholes because their own life is just terrible and not a question of religion.
There are problems in some German cities and I know what I'm talking about since I live in the "Ruhrgebiet" where there are many Muslims but I think many of these problems have not much to do with religion at all. Especially some younger guys from countries like Turkey can be pretty annoying from time to time (calling you some bad shit on the streets and being very aggressive) but that's not because they are Muslims, it's because of their situation and perspective. Kids without much perspective from German families are also fucked up pretty often.
If companies start to give these people also a chance to work for them, if politicians learn how to handle these problems they are mostly responsible for better than they would be also much better integrated and if they would see how great life can be with such a system we have here they wouldn't want to get a worse one even with more power.
Not to forget that it will take still a very long time in most European countries to get a percentage of Muslims which would be so high to really change much. fertility rate is higher for these immigrants but statistics also clearly show that it's mostly the first generation coming to Germany and that as example the fertility rate of Turks in Germany is also already pretty low nowadays since most live in second or third generation here.
And just to round this up, most immigrants in Germany aren't even Muslims (they come from Poland, Hungary and so on) and with countries like Turkey we even have a negative migration, more Turks leave Germany as they come to Germany (at least in 2012) and you can be sure that some of the people from Syria and other countries will also leave Germany again if situation will get better after ten years or something...
What I can't stand is that some don't even try to learn German to get a better chance and to contribute more to this country but that's not a Muslim problem, I also see that from people who come from Bulgaria, Russia and so on...Same how some Germans live in Spain and can't speak a word Spanish, I find that horrible and a shame.
There are some negatives but there are also positives. I am at least very happy that I get so much different food on the streets and I love to go to Turkish greengrocers 
