Is it worth trying MonetDB?

Has anyone had any experience with MonetDB? Currently, I have a MySQL database that is growing too large, and queries are getting too slow. According to column-oriented paradigm, insertions will be slower (which I don't mind at all), but data retrieval becomes very fast. Do I stand a chance of getting more data retrieval performance just by switching to MonetDB? Is it MonetDB mature enough?

You have a chance of improving the performance of your application. The gain is, however, largely dependent on your workload, the size of your database and your hardware. MonetDB is developed/tuned under two main assumptions:

1. Your workload is analytical, i.e., you have lots of (grouped) aggregations and the like.
2. Even more important: your hot dataset (the data that you actually work with) fits into the main memory of your system. MonetDB does not have it's own Buffer Manager but relies on the OS to handle disk I/O. Since the OS (especially windows but Linux too) is sometimes very dumb about disk swapping that may become a problem (especially for joins that run out of memory).

As for the maturity, there are probably more opinions on that than people inhabiting this planet. Personally, I find it mature enough but I am a member of the development team and, thus, biased. But MonetDB is a research project so if you have an interesting application we'd love to hear about it and see if we can help.