With the new QML version of the Ovi Store client now standard on Symbian^3 and upwards, it's interesting to see a brand new version of the Store client for S60 5th Edition now available, v1.22 (the previous latest was 1.16). There's no official changelog, but following new versions of the QML Store, it's likely that the new client is better 'aligned' with changes to the Nokia Store back-end.
It's an optional, rather than compulsory, download, but it also seems to have better performance, so go for it if you have an older device.
To get the new version, just start the Nokia/Ovi Store client and you'll be offered the download. Note that this is effected through Web (briefly).