I don't think that users will have a hard time figuring out the C-Valve at all as everything is pretty easy to understand. The pre has knobs for input gain, low frequency cut, saturation, and volume. It also has buttons for mic/instrument selection, phantom power, phase, low cut, vocal EQ, enhance, and limit. While the vocal EQ and enhance are simple preset EQs that are traditionally seen on mic pres, the rest of the parameters are either widely known or are self explanatory. I haven't seen a manual for the C-Valve, but judging by how easy it is to use I don't think that one is necessary anyway.
The sound of Samson Audio's C-Valve isn't anything to write home about, but it is definitely serviceable enough to be used in a home studio setting. The sound quality isn't up to par for professionals in my opinion, but it good enough to be used for demos or for smaller project sessions. It is a pretty versatile pre because of the parameters that it has, but I'm not a fan of the 'vocal EQ' and 'enhance' settings as they are preset EQs that don't apply for most situations. However, it is definitely nice to have the low cut feature as it allows me to cut off the low end on applications where extreme low end isn't necessary.
While the Samson Audio C-Valve would never be my first choice for any sort of recording whatsoever, it is definitely a suitable option for home studio owners looking for a tube mic pre that will give you some bang for your buck. It has a decent enough sound quality driven by a tube that makes it perfect for a small home studio owner looking for that tube sound without having the spend too much money. C-Valve is in the same vein as PreSonus' TubePre as it is the same price and is overall a similar product. If you are looking for a bit of a warmer sound from your pres that you are not getting with your stock audio interface pres, C-Valve is definitely worth checking out.