Of course, processors that use one of the Atom/Celeron/Pentium microarchitectures are not the best choice if you desire maximum speed, but otherwise they are surprisingly interesting processors (IMHO much more interesting than what Intel delivers with the Core series).

At this time, Intel often experiments with or introduces features that are particularly interesting for embedded usages first on the Atom. For example the already mentioned SHA-NI. Another example are the MOVBE instructions (insanely useful if you handle big-endian data, for example in network packages (I am aware that on older x86 processors, there exists the BSWAP instruction)) - they were first introduced with Atom.