I think the write speed is more determined by the card than the adapter.
About the only technical difference between boards is that some are 3.3v only, some are 5v like this one, and some have pins for both. I believe the only other consideration is physical. This is not a shield, it is freestanding, and would not be a good choice for installing on a shield, as the pins are on the wrong side..
There is probably nothing dirty about this board, unless you have a thing about buying cheap stuff from China.
An SD adapter for twenty times the price probably does a lot more. That price sounds like it is actually an ethernet shield with SD included. On that matter, it is common to have SD included on other devices like ethernet and display, and you may find you don't need this.