Dynamo is in essence a stripped down version of Reaktor with the sound engine of Reaktor 2.3 (Reaktor is currently at 3.06) and the premium library that is also available for Reaktor.
There is good diversity in the synths you get and when first introduced Dynamo was a reasonable value. However in 2002 it is poor value as it is based on the older Reaktor engine and has minimal support, nor did Native Instruments live up to the promise of new ensembles. A few were released but for the most part what you bought was what you got.
Admittedly the quality of sound and the diversity of ensembles are good ranging from several drum and synth sequencers, a few excellent subtractive synths - in particular the Uranus ensemble which has a smooth and big sound. Also, the hints of sampling and granular sampling are at times spectacular if somewhat abstract.
If you find the package priced around $100 get it and known you will be able to upgrade to Reaktor Sessions which allows import of all Reaktor 3.x ensembles, effects and instruments.
For most people this will amount to a substantial upgrade and a most worthwhile one. Many Reaktor users put together preset synths and hardly ever get into the depths of programming it.
So consider Dynamo if you can find it on sale. It will give you a taste of the Reaktor sound from a couple years ago and provide you with a reasonable upgrade path to the much smarter designed update.
Otherwise pass on this package and look for one of the better software synths such as z3ta+ or Albino. They are better synths and have substantial feature sets.