What are the disadvantages of Ethereum?

Could you elaborate on the potential downsides of Ethereum? I'm curious to know about any scalability issues it might face, as well as any concerns surrounding its security measures. Additionally, I'm interested in understanding the challenges it encounters in terms of transaction speed and cost. Could you also discuss any regulatory risks or limitations that might affect its usage? It would be helpful to get a comprehensive overview of these disadvantages to better assess Ethereum's overall suitability for various applications.