I need to know if the adjective "plain" sounds neural or negative in some manners? If the latter is true, can you give me a better, positive alternative to the word? "Simple" would not work either, I guess. Or maybe "unadorned" could work but it is too long a word to use in a casual way.
addition: sorry, I totally forgot to mention the context. The context is the overall decoration of a place such as restaurant or cafe. Also, the context could be food-related too. e.g. "a plain birthday cake"
Thanks in advance!