They are plug and play solutions, and have no drawbacks. But since they are intended for mining only, you should not expect to have an adequate experience doing anything else (ie using a browser).
If you can set up Linux to mine properly with the proprietary drivers and all, it will be exactly the same.
Of course they have drawbacks. Simplemining doesn't support Nvidia cards at all and EthOS doesn't officially support Nvidia cards, but can be done if installing drivers and miners etc. manually. But at that point you could just go with any Linux distribution and install drivers and miners manually - making EthOS obsolete.
