I've used google sitemaps on about 4-5 of my sites and noticed no recognizable increase in traffic from google (no more indexed pages than sites without it). Has any webmaster had better success with the sitemap?
I uses sitemaps only in sites with more than 2/3 new pages per day. I haven't noticed traffic benefits but I see pages are indexed more quickly than usually. It takes usually no more than 3 days to include all new pages in SERP.
I regularly submitted my sitemap xml squarehippies.com to Google sitemap whenever I update / add a page and I noticed it got indexed rather quickly based on the sitemap. No significat traffic increased though. My site only over a week old.