Alignment is, of course important when rolling any character. As for dwarves, you could chose any alignment you want, but remember that tha vast majority of the dwarven race is tending to be either LN or LG, and imo LN would be the most common. These are the alignments to chose if you want your dwarf to be comfortable with the clan, family and intricate rules and traditions governing dwarven society. If you are chaotic (or evil for that matter) you probably won't and will be a loner or a bit of an outsider in the dwarven community.
Now here are some typical traits (or flaws) of the dwarven personality and values:
Racist, suspicious, grumpy Dwarves often comes from isolated enviroments in enclosed underground societies and often have isolationistic tendencies. They have deep rooted prejudices about elves and see them as whimsy and unreliable. Orcs is a racial enemy of the northern (shield) dwarves, so they tend to be very reserved about halforcs. The southern (gold) dwarves have the same feelings about drow. Dwarves (and most of the elder races for that matter) regard humans as unstable, unreliable and hard to put a finger on (elves are unreliable, orcs, drow etc. are evil, humans are... what?). The typical dwarf is probably quite sure that dwarves are a bit superior in many respects and would prefer the company of other dwarves. If you mix with other races, you may never know where you might end up...
No greyzones Dwarves tend to have less moralic greyzones than other races. Things are either good or bad, good or evil. And when your dwarf have made up his/her mind about it -damn if anyone could change it.
