I had an opportunity to buy a copy of Deathwatch Overkill at a discount over the weekend. I didn't do it. The models are cool looking. They're definitely worth it from a modelling and painting perspective. Seriously. These look cool and you get lots of them.
I didn't buy them because I don't know if they're any good. I also don't have any real solid way of finding out that they're any good without buying a copy of the Codex. Yes, GW put out some free datasheets giving us unique, named versions of the above models, but I don't know if the Genestealer Cults faction is worthwhile to invest in. The most affordable version that has all of the content is 32.99 USD and requires a computer or tablet to read. If I want a physical version, I have to spend 50 USD. It just feels like a lot. I wish GW would just give their unit rules away for free like almost every other game out there.
There have been lots of rumors swirling around lately that 8th Edition 40k is going to be coming out soon. I'm REALLY hoping they pull an Age of Sigmar maneuver and give the unit rules away for free and make the faction rules available at a low price. 30-50 USD for a Codex is just a lot. I'd rather be spending the money on models.