You essentially have 40-70 extra cyberware capacity + the trade-off of not having an operating system (which in some cases you save up a ton of cyberware capacity). Of course you don't benefit much from it doing a netrunner build (unless you're nuts about smart weapons and hate quickhacking) and a bit for stealth and cool builds. However anything else you're set to go, especially for the good ol' body/tech builds. You obviously lose the edge from berserker or sandevistan OS, but as a trade-off you can equip many of those iconic cyberware upgrades and you can become a monster overnight. Of course it might make some builds less efficient (quick hacks and sandevistan/sword builds for example), but for many other cases the trade-off is worth it.