Yes of course they help, but we are not talking of reciprocal links from crappy and unrelated websites.
It true that search engines give more importance to one way links compared to reciprocal links but, as I was saying it depends on the quality of site in question. It doesn't mater if the link is reciprocal or not, a good link is a good link and a low quality link is a low quality link.
One way links from unrelated websites, or from low quality ones will do you no good. The most important factors in link building are link relevance and quality.
Also It is best to use all tactics to build links.