Interestingly enough, I had a recent start where an honor opening just fell into my lap. I started coastal and decided to move my settler inland, because I'm not a huge fan of coastal starts. Turns out I ended up right beside Darius's capital. So, I said to myself: "If this isn't the ideal situation for opening honor, there isn't one." I hit him with 1 spear (upgraded warrior from hut), 2 warriors, 3 archers, 1 scout, and 1 great general at turn 28. His capital went down no problem and he was gone 2 turns after dow. Annexed the capital to build more units.
Then I looked around at my surroundings. I was surrounded by CSs and had Hiawatha further to my south below a row of about 3-4 CSs. Turns out Celts were to my SE in the fog and I found them later, but they were a non-factor early.
So, I said to myself: :shrug: "I have a huge army and no money to befriend these CSs, I might as well attack them." I conquered 3 of them (and was surprised I didn't end up in perma-war with the rest -- when was this changed???). The last one I took was very close to Hiawatha's 2nd city. So, I used my 2nd GG as a citadel and declared on him. He had *just* took over largest army, which I had, had up until that point. He had swords and I didn't, but I had CBs. I took his 2nd city and whittled down his army until he gave a generous peace deal, which I took so I could upgrade 4 warriors to swords to finish him off. It was at this point that I discovered Celts, who were weaker than me (I was back up to largest army) and saved and stopped. Hiawatha would fall. Celts would fall. Other CSs would fall (there were still quite a few on a fairly large continent). I would end up with somewhere between 10-20 cities without ever building a settler. I would own my continent.
Observations:
1) On top of largest army, I also ended up with largest empire, most production, highest gdp. The first CS I conquered had Mt. Fuji, which I used to get a religion going. I took god of craftsmen, which helped with production, especially courthouses. Definitely good for early warmongering, can't complain there. I built warriors/melee and bought archers. However...
2) I also ended up with lowest population and very poor science. Combined with 1, to me, this means that as long as you can steamroll your continent without encountering someone who has out-teched you and can defend themselves (i.e., the brick wall), you're golden, as you can recover your economy once you've cleared your continent. However, if you hit the wall, you're screwed imo, as you have no infrastructure to fall back on really. So, I can see where this is pretty problematic at immortal/deity. However, on levels below that (I play at emperor), you can be ok.
3) I went full honor and didn't mix with anything. Oligarchy would be nice at some point, as I was bleeding gold pretty bad a lot of the time, though bullying a CS at one point for 100 bucks made all the difference. Happiness was also difficult. I just aimed to stay above -10 and targetted the CSs first who had unique luxes. Hiawatha's second city and capital both had unique luxes and Darius's had 2 unique luxes as well, so I was generally ok, especially once the 1

per garrison sp came online, which also helped push culture. The cheaper upgrades across a large army like that are great, though I find they come too late for CBs. Great for swords and onward though. I hadn't run into enough happiness problems yet (nor did I have a ton of spare production) to start putting in walls, though I would eventually, which would be nice. Honor really does offer a lot to a wide empire in terms of

I really like the idea of building melee and buying ranged, but you do have to get yourself some workers and trading partners before you start bleeding gold too bad though.
4) Never built a worker. Every city/CS that I captured had one, so I was golden there. Never needing to build a worker nor settler means you can focus pretty much exclusively on producing military and your most-needed buildings (i.e., courthouses, markets, libraries).
Overall, I would say that honor is only lacking some kind of economic benefit in the first half of the tree. If there was any kind of economic benefit to either help with infrastructure or unit maintenance, honor would be pretty powerful in the right circumstances, at least up until emperor. Can't really speak to immortal/deity, since I don't play at those levels, but I can see how honor would really pale compared to tradition/liberty as it does run out of steam once you realize how little science you are pushing out.