That’s can do on a wordpress.com blog. There are however other free third party visitor tracking systems we can use and if you click my username and look under “Visitor Tracking” you will find them on my Popular Posts page.
See also > http://en.support.wordpress.com/stats/
If you don’t like the selection of themes, and you want to use Google Analytics (above and beyond the use of it that WordPress.com makes and reports to you) then WordPress.com is probably the wrong place for your blog.
But there are lots of other places you can get WordPress hosting, such as those listed at: http://wordpress.org/hosting/