Pentagon was the 1st soft synth I had good success with in fully automating and programming it from within Cakewalk Sonar (version 2 at the time). Finally everything worked like it was supposed to, the MIDI learn features were solid and versatile, it had enough oscillators to generate some really nice sounds, as well as enough envelopes to really shape every step of the process. Really the only way to get the shaping features more flexible would be to use a mod matrix similar to what you find in rgcaudio's excellent z3ta+ synthesizer.
Since this synth is skin-able, there are some very attractive skins on it, so I would recommend you look into those, they are very easy to implement and the new look could very well improve your music creation process. Rene has a good following of friends, and customers online and from this community comes some great presets for the synth and skins. It really is a grass-roots built instrument and it's care in detail and quality shows in it's sound.
I used this synth for recordings on an album, then got into Reason for an album, and now I am back and pleased to find the latest updates for this synth add some new features and sounds, like the wavetables. It is nice to see Rene continuing to work on this product even though he has newer machines out.
It is true that this is "just another virtual analog" in that it's feature set doesn't boast anything that your auntie's soft synth doesn't also do. But I think that everyone needs to find their preferred virtual analog and make it "theirs" (or for the collectors amongst us, make it "one of theirs") in that you really take the time to learn the instrument inside out and figure out the nuances of it that sets it apart from everything else. Pentagon is that synth for me, I have used it over and over and it still has the sounds I'm looking for when it comes to analog. It has just enough features without the interface getting TOO rediculously large and it getting too bulky to tweak easily. It is a great balance between power an functionality, and with the support in the forums, the user community behind it, and the sound banks, it is easily worth paying for this instrument when you could conceivably find the same list of features on a freeware synth somewhere. A lot of expert thought and testing has gone into the development of this instrument, and it shows.