Ellis’ work on Excalibur is not of the quality of Stormwatch or Planetary, but it is very good superhero work. Despite his current distaste for writing ongoing superhero books, I think it’s an excellent form for him. Working within someone else’s continuity must be a pain in the ass, but the challenge seems to bring out his ingenuity.
It doesn’t have the same overarching story that his other superhero runs have had. He did a couple of good arcs, including the superb “London Burning” arc, and you can see him working on developing the style that led to the longterm plotting of Stormwatch, but this is definitely early Ellis. The characterizations are awesome. He turned Kitty Pryde into an adult, and Pete Wisdom is a neat anti-hero without being anything like Wolverine or Gambit. He’s an adult anti-hero. You don’t get a lot of that in superhero comics.
I’d recommend seeking out issues #83-103 of Excalibur, along with his miniseries, Pryde and Wisdom. You can skip the Age of Apocalypse stuff, which was four issues under the X-Caliber title. Slogging through the crap was worth it for the Ellis, but you shouldn’t subject yourself to the same pain and his issues are completely legible even if you haven’t read any of the earlier material.
I have also read all the Ben Rabb issues, which conclude the series, but I’ll talk of those when I’ve regained my strength.