Ironhead Spawn features numerous softsynths in a single product. The package focuses on percussive sounds, with an emphasis upon percussion that can be sequenced melodically. These synths are quite easy to use--even their names are intuitive things like "bash" and "ding". Each comes with an impressive array of pre-sets, which are logical extensions of the instruments using a range of parameters, rather than the "hey this is weird" detritus that sometimes affects softsynth pre-sets.

I've been playing with these synths since soon after I bought them, and I pronounce them "effective and easy". I use them in the simple [Bram Bos] Tunafish sequencer, in which they operate efficiently and generate a good sound. I found that when I apply my sequencer's flanges, gates and delays to these synths, I get very pleasing electronica sounds.

The GUI on these synthesizers is simple and clean. My only minor problem is that the synth GUI tends to "pop up" once in a blue moon after I have set it and minimized it, but I am not sure at all if this is a "synth issue" or a "user error" issue. Also, sometimes I have had to focus on making sure I am getting enough volume from the synthesizer called "ding".

I make ambient music most of the time, and these synths will be great for adding percussive elements in unorthodox ways to dark ambient pieces.
Today, though, I completed a more conventional electronica piece, which I reference for those who'd like to hear the synths in action (interfacing with Creative Commons samples--they're the percussion in the main melodic sections]:

http://ccmixter.org/files/gurdonark/21698

This collection of synths is an excellent buy--well thought out, and targeted for the creator who'd like a dependable set of instruments without the calculations and complications of Buchla-like programming.
An artist could use this as a one-stop synth which, with a sequencer, would be virtually all one needed to easily create original music. That's because unlike some percussion synths, Ironhead: Spawn is intended to permit one not only to bash, crash, and thud, but also to do melodic thins like ding. It's a solid ping/bop experience.