Their solution does have a few gotchas but I've been using it quite happily for a couple months now and believe it would be a workable option for many. Before diving in there are a few things you need to know: the solution requires a couple steps and is a little technical, you need to have your own blog domain and, since CloudFlare uses DNS, if they go down, so will your blog. On the plus side, CloudFlare is free, has a number of cool features, and is fairly safe and easy to try out. I'm pretty sure there are wordpress.com bloggers who could get this going in 5 to 10 minutes.
If you're curious about what's involved you can read my post detailing the experience and the steps involved in setting it up: http://jonathonbalogh.com/2012/05/07/how-to-use-google-analytics-on-a-wordpress-com-blog/
I'd love to hear from other wordpress.com bloggers who give this a try. Please post your experience below.