I've picked up a couple of the Oilbrushers on a lark and I'm on the fence with whether or not I like them.
On one hand, the stuff is thinned compared to regular oil paint and ready-to-use straight from the bottle. The range is full of intuitive names, like "starship filth", to give modelers an idea of what applications are appropriate. For those of the "Spanish school of modelling", the stuff is a good fit.
On the other hand, there is a learning curve that those who don't necessarily follow the techniques espoused in that school of thought. If you're not used to dot filters or working excess oil with a cotton swab and turpentine, it can be frustrating.
The 'mascara' tube packaging is something you either like or you don't. I don't care for it, but that's personal preference. I'm not sure if the bristles on the tiny brush inside the cap are synthetic or natural bristles, but that's really a moot point.
There's a strong parallel in Tamiya's panel liner products and they are somewhat similar in consistency and application, but with more colors available. If that's your thing, then by all means, try it.