I bought like 2 of them so far and they both were exactly as expected. The only thing to note is that you should try to find those with CPUs (are those CPUs?) similar to the ones from the original designs. Some (the super cheap ones, < $1) often are identical by design but come with some crappy CPU
Almost all the ones I've seen have used the atmega328P. You might see some slightly different models with different amounts of ROM and RAM, but most people would probably never notice the difference. If you need more than a few KB of RAM/ROM, you should probably be getting something STM32 based instead.
What does change is the Serial > USB converters that they use. The more expensive ones (>£3) tend to use FTDI chips, whereas the cheap ones use a CH340G or a similar part.
On some platforms you may have to install drivers to make these cheaper converters work, but they were just plug-and-play for me on Linux.
> If you need more than a few KB of RAM/ROM, you should probably be getting something STM32 based instead.
Which might not be a bad idea anyways. The Arduino framework's been ported to STM32 (stm32duino.com), and you can get a board and programmer for under $10.
