canvas is definitely good to go for modern browsers. If you want to support Internet Explorer 8 and below, ExplorerCanvas and FlashCanvas can be helpful in providing support for most
canvas features. However, due to the complex nature of native
canvas implementations, developers should be aware that the polyfills for
canvas are not simple drop-in solutions in some cases.
For example, both ExplorerCanvas and FlashCanvas may have difficulties handling the commonly used
drawImage method. FlashCanvas cannot be passed the bitmap data from a DOM-based
Image object, and therefore has to re-request the asset in the Flash Player causing undesired latency and flickering. Developers should be careful when handling image data and ensure thorough testing due to the unreliability and technical limitations of these features in the polyfills.
That isn't to say
canvas shouldn't be used if cross-browser compatibility is a concern. Existing polyfills are more than capable of rendering simpler bitmaps such as charts/graphs, visualizations, and even starfields! For these uses and many more,
canvas is highly encouraged.