Is being the second author always good?
This depends strongly on the field. In some, it is a big deal, in others not so much. But it is always a good thing to be an author, wherever you appear in the list. 

If you are comfortable with it, don't worry too much. Your preferences may change, of course, in which case you may want to take more of a lead in the research and thus in the "perceived rank" of authorship. 

Of course, your institution might put more emphasis on "first" authorship and it may affect your advancement. Don't neglect that. 

In some fields we don't worry at all about that and just list names alphabetically, assuming that if they are listed, they contributed.