Betaseron (the US version) has been around for a long time. I've been on it for at least 12 years. It (and Avonex and rebif) are all interferon-based drugs, so the side effects are generally the same for them, and they are different than what you might have experienced with Copaxone.
Prior to starting the BEtaseron, I was experiencing 2-3 exacerbations a year. After starting it I had one, about 2 years into injecting, then none since. Note none of my symptoms have improved, and I was significantly impaired by MS before I started the Betaseron, but none of my symptoms have worsened significantly, either, so I consider it a success.
If you have specific questions about side effects, just ask!
...I am not a doctor, nor health professional, and don't pretend to be one, here.....