It works very well for me. My evidence that it is private is that I download plenty (more than 1 TB per month) and I never get a copyright notice from my ISP. When I torrent non-privately I get plenty of copyright notices, sometimes several times for the same torrent.
It does have, however, some major performance issues. It can be very slow, and it can use up a lot of RAM and a lot of CPU. Its internal database, which saves state of downloads, frequently gets corrupted at which point it has to be re-generated, meaning the list of torrents (not the downloads) is lost. It can be quite a bit slower than other torrent downloaders, and sometimes torrents stall for a while as it waits to prepare the network, especially at start-up.
It's been getting a lot better though with every update, which is quite frequent.