First if you're looking for a VRMMO LN this one is probably the best. However while it has a lot of qualities, it also come with some issue, mainly on one part: the characters, the problem isn't really with they're devlopement or personality because aside from Rook most of them are quite good and even if the main characters can be a little too similar to shounen protagoniste at time he is overall quite interesting, the problem is with the power system link to those characters. To put it bluntly it make little sense a lot of the time, the system in itself is fantastic (onof the force of the serie) but it's use isn't, with vilain wich tend to either have powerfull but balance power or no power at all while the good guy power have little weakness and are quite op at time, that plus some characters being op outside of the power system and you get the true biggest problem of the serie the MC allway won.
But on the other hand a part where the serie is great is with the NPC, wich in that game are like real persons, the way they view the world, the players, the eventual fear of the player ( wich for them are imortal and op transdimentional being) or for those who are aware of the game nature of the world how to live with it, is the best part of the serie and it's what make Nemesis one of the best character, because many of the questions it raise are really interesting and for some of them kind of unique to the serie.
To conclude the serie may have a problem with its power system/ MC allway winning, but it's definitly worth your time with some great characters and world building.