In PortaMatic you'll find a collection of analog sounds, sampled from Yamaha PortaSound MK100 and a Wersi Matic CX-1, along with some custom additions. Most of the sounds are dry, while some are processed just a little bit.
If you want to go a little crazy, try playing around with the long spring reverbs we sampled for the Snare Drums 2 group using a classic Roland RV-800 spring reverb. Using the hold and Spring Decay settings creatively, you can make a really cool sounding gated reverb - combine this with individual pitch via Note Edit for an all 80s experience :-)
PortaMatic is probably best described as "just really analog", and certainly has a distinct vintage vibe to it.