Speaking from the perspective of a Baptist with a Lutheran grandfather, and the precious little research I did:
http://linetap.com/trinity/trinity2.htm
Lutherans are Christians of a sect that is midway between Protestant and Catholic. They have creeds and sacraments, but are not part of the Catholic church.
In a practical sense, there is probably very little difference between the rest of the Christian faith. Lutherans might have a bit of a problem with the Catholic faith as it is sometimes not considered truly Christian (the whole Saints thing sometimes goes against what they believe is the very essence of Christianity) and they hold the scripture as being the only authority on the requirements for salvation.
As for a more on-the-surface description of the church and services, the congregation in my experience can be characterized as "old". Lutheran churches often have a problem with numbers dwindling due to death from old age.
In summary if you are Protestant or Catholic you should not have any huge hurdles in theology to overcome.