This level is pretty high quality, with good attention to detail and pacing. It's not very hard or heavy on opposition though, though you may still be glad you have items in the inventory once in awhile. The problem with this level is the rather confusing progression. It can be solved if you take your time to check the automap for clues, but won't work if you're impatient or in lack of time.
HINT: at one point you'll encounter a small wooden door behind a priest bas-relief hidden door. There's no clue whatsoever, but that door needs to be shot to open! I had to open the editor to find that out, as no information got provided about that.
This wad seems to be a compilation. Anyway, here goes the per-level reviews:
An average dock level. Water hurts. There's an unusual way to wade through this water to open some barriers. Overall pretty blocky and not that well done. It's plagued by REJECT errors causing most monsters to be passive against you.
A dungeon level made of copy-pasted layouts. Overall much better and more slaughter-like than the previous map. Relies on switches and passages for the greatest part.
An even better and much harder level. This one involves some wicked layouts of passages and lifts, and uses symmetry to its advantage.
Overall, some super challenging levels but not very strongly structured, rather on the more abstract side.
The original "Eternal Doom," which makes up the first 12 maps of this Megawad, is an absolute must-play masterpiece. The levels are huge, yet finding one's way about them is an enjoyable task rather than a maddening chore. Hexen and Heretic both have beautiful textures, and the maps use them to great advantage to create sprawling medieval architecture and display some of the best environmental story-telling present in any wad I've ever played.
However, that praise does not carry on to Eternal Doom's two expansions, dubbed, "Eternal Doom II" and "Eternal Doom III," created by TeamTNT, which make up maps 13-32 and are, at best, an incredibly mixed bag and worst--well--painful. Beautiful architecture and intuitive layouts are traded out for strange abstract maps with misaligned textures and an overall quality that feels better suited for something like "D!Zone."
Most of the maps aren't awful by any means (Actually a few of them are--Map 14 comes to mind), but it almost feels unfair to put any set of maps after one of the greatest 12-level episodes of all time.
It should be said that the weakest the Megawad gets is "Eternal Doom II," as part III as a whole finishes strong, aside from a bloated copy-cat of map 12 that stands in the map 30 slot.
The soundtrack, composed by Rich Nagel, is the most consistent bar of quality throughout the wad, and almost--ALMOST--makes the more mediocre sections of the map-set bearable, providing an incredible score with returning themes and varying styles.
On the whole, Eternal Doom I is easy to recommend, and to the most diehard fans of the wad's esthetics, may just buy enough good will for those who wish to journey forth for rest of the megawad's offerings.