They are both correct, but the sense is a little different. In the first one 'welcome' is being used as an adjective. The second one is a passive construction--'feedback is welcomed (by us)'. Even though they mean basically the same thing, I like the first one better. The active voice is simpler and sounds stronger. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.