Good when it works, with a limited number of available servers. However, 1. Does not always connect to the fastest server. 2. On the Mac, it does not automatically connect to a server. 3. On iOS, it does connect automatically BUT does not do so consistently. 4. The Mac app has been buggy and not connecting at all, FOR MONTHS. They still have not fixed it.
Although ZenMate has a dedicated server for BBC iPlayer it does not work. I contacted ZenMate support about this. They said they knew and are fixing it. One month later it still does not work. I cannot recommend ZenMate for BBC iPlayer. I switched to ExpressVPN as a result.
No matter your location, using a VPN is important for your online security. I got ZenMate for exactly that and I am satisfied with it, especially when it constantly improves its service. Customer support helped me so much and I just wanted to say that I've asked for their help a few times. And every time the support was respectful and fast in their response time. Keep it up!