I have been using Redis in different projects during more than a year now and Redis has become a part of my standard "stack".
It's a good hammer, thanks to it's list-set-hashes-etc support.
A quick scan through there doesn't show anything hugely new and exciting, but a lot of good, solid improvements, all packaged up in a in a stable release.
Basically we'll try hard to don't add things to the API in the next releases, but just to open to new use cases changing the "backend" part, with cluster support for large fault tolerant deployment, and with diskstore for "bigdata".
However there are a few important new things in Redis 2.2 from the point of view of the features, I think the main ones are:
* non blocking replication, so that now slaves are able to serve data even when trying to resync with the master.
* Check and Set with WATCH.
* Write operations against keys with an expire set.
* LRU eviction of keys in 'maxmemory' mode.
* Support for SETBIT/GETBIT/SETRANGE/GETRANGE, basically this turn the string data type into a random access array.
But warning, very old clients will not work as 2.2 completely dropped the support for the old protocol, that was only "discouraged" with 2.0.