It's true, to an extent, but not because migrants bad. You can look at this, but the short of it is that the stats you see in the news are like that mostly because they're counting illegal immigration and illegal stay as crimes in their stats, which as you can probably guess is pretty flawed. You remove that and the numbers look... still bad but a lot more realistic. Then you realize that migrants are more likely to be poor young men (aka the demographic most likely to commit crime). As the article explains, Syrians for example are actually underrepresented in crime stats, because they tend to be complete family units (most Syrians in Germany were allowed to bring their families over) so the demographics are more representative of a normal society.