Too bad SM is Windows-only and desktop-only. The beauty of Anki is that you can review anywhere.
On linux you can use SM via vmware/wine and on os x it's quite usable with parallels. If you're using SRS just for language learning then being able to use on mobile can be helpful but I think for those cases supermemo.com can be a decent alternative. More generally, I think the platform specificness of SuperMemo is more than made up for with its incremental reading functionality (alongside better scheduling algorithm)
> On linux you can use SM via vmware/wine
To add to this, there's a set of Winetricks recipes for running SM on Linux.[0] (Disclaimer: I haven't tried them, though I've been planning to, for a while.)
If you use SM and you use anki both for a significant amount of time it's not hard to see that SM leaves you with way less reps. Anki is based on the very first version of the SuperMemo algorithm (from ~1990 or so which was the first SRS algorithm ever) known as SM2. Current version of SM uses SM18.