The widgets work best on devices with a portrait QVGA screen, although you should be able to use them on devices with other orientations or resolutions.
The widgets range in quality (mainly due to the underlying code), but everyone should find something to keep them happy. Such short puzzle games can be a great way to pass a few spare minutes of the day.
Three of the 50 Widgets: SameGame, Teris and Dots
WRT widgets run on all S60 3rd Edition Feature Pack 2 (N78, N96, i8510) and above phones. Many S60 3rd Edition Feature Pack 1 phones can also run WRT widgets, although they may require a firmware update (e.g. all Samsung devices, Nokia: N95, N95 8GB, N82, E90, E66, and E71.