I first bought Pentagon at vers. 1.0, but never really liked the sound (IMO it kind of lacked depth or breadth - fuck, it's difficult to explain) or GUI (dark/confusing), so I never really used it. With vers. 1.3 this has all changed --- I'm a true believer now!
User interface: Beautiful & Logical. The skin for 1.30 really does wonders. Knob inertia ...mmm. Virtual wood ...aaahhh.
Sound: With 2x oversampling the sound comes close to true analog. IMO one of the best analog emulations so far, even rivals the MMV.
Features: Contains almost everything you need for semi-modular analog modelling, even good quality effects. Could use some more pre-defined waveforms, though. Why not throw in all the waves from z3ta+?
Documentation: Generally quite good, but the sections on user samples and pentagon as fx/vocoder could IMO be improved.
Presets: A lot! And good ones, too --- perfectly showing off Pentagon's capabilities as an analog emulation. Many more to download from KVR.
Customer support: Well, just see how active and responsive René is on KVR. Says it all.
Value for money: Absolutely. Compare to e.g. MMV at $250.