I must sya I have to disagree with vast majority of the comments so far.
Similar to user: Its_Ya_Boi_Lava - I have started reading this series with no expectations whatsoever and I must say that while it's not perfect, it's far from how badly majority of you had rated it and described it in your comments.
For the first time so far I have seen a proper VETERAN special ops soldier as an MC in an apocalyptic series with an upgrades system involved.
So on the matter of the MC being OP as fuck and supposedly soloing everything:
1) From the get go, before even geining any sprt of superpowers the guy was built like a bull.
2) on top of being built like a bull the guy has mastery of close quarters combat, several weapons and guns, present really high level of fitness and his military experience also explains his knowledge of tactics and ability to continue operating under stress while maintainging calm and level heded approach.
3) Sure, he does solo some of the hardest monsters, but as far as I have seen it was because his troops have not been able to cope with that level YET - he made an entire organisation, with divided roles or each of its parts and his followers also fight and slowly but surely gain in power. From my point of view it makes sense to send out the strongest unit of yours to deal with the strongest enemy - that way you can save human resources from being needlessly killed by a threat they wouldn't even be able to harm in the first place and allow them possibility to grow stronger later. From my point of view it's a very logical approach. Very humane as well, considering the whole post-apo scenario.
On the matter of being stone-faced:
1) the guy is a veteran of a spec ops unit - a battle hardened cookie that eats a hammer and shits nails
2) until the start of the plot he is suffering from: PTSD, Suicidal Thouhghts, Drug addiction.
Given the above it's rather obvious that his expressions would be limited if not non-existent altogether - please refer to the general psychiatry textbooks available in your country - you will see that people suffering from the above, especially PTSD often demonstrate a lack of emotions and expressions aside from the sudden flashbacks of their trauma.
So while certainly imperfect it is FAR better than majority of commenters made it out to be. I'd say around 7,5/10 maybe 8/10 at times.