Personally, I didn't enjoy the Infernal City. The chapters set in Cyrodiil were very cool, but the chapters set on Umbriel were too "Alice in Wonderland"-ish for my tastes. Very fantastical, more Shivering Isles than Oblivion.
I'll be skipping Lord of Souls myself. Infernal City was, for me...definitively 100% "pinnacle of mediocrity" sums it up. Not bad per se...but nothing to recommend it aside from the TES tie-in, and even then it felt burdened by "forced product tie-in" writing. Even the parts in Cyrodiil, for their coolness, sort of beat you over the head with descriptions of gameplay mechanics that felt forced.
Which is to say, I found it to be a typical videogame-based book overall. Fun for the tie-in, and otherwise utterly unremarkable
at best. :shrug: