1. I found the quests themselves are pretty easy. I think it's the guardians that make the pyramid quests a bit more challenging. The fossil gather rate is a bit low, even gathering more than 3 stacks and still not getting 5. I can't say I find dailies interesting as they're routine, but it's nice that 2 of them aren't your typical kill quest.
2. It's hard to tell which bounties are inside the pyramid or not. I have to do a long press on the bounty names to be able to see the kill count to tell, but for newer toons, they might need to ask others or look up a list on the wiki. I also had trouble finding the pyramid entrance initially as I couldn't find the other pyramid on the map.
3. I feel that the guardians hit harder than they should, for the amount we have to kill. To be honest, I would be a little sad if they're nerfed a lot lol. It was tough, but I found killing guards doable on all my toons with on-level gear, even my level 38 hunter. It is a pain running back when doing pyra bosses though! If the zone is meant to be tackled as a group, I feel that the challenge level is fine (although the stuns are still too long). But getting help from the community makes the daily feel less of a chore with company.
4. They are okay. They don't take that long to kill, which is nice. But I think they don't really do anything interesting except stun.
5. I think this ladder manages to strike a good balance between last event's regular and emp ladder in terms of difficulty. I appreciate that they don't take too long to finish. Geb, I find less interesting as you can just stand between the fireblowers. Aten's lightning feels as if my screen brightness is cranked up way too much. I wish this was toned down a little as it can be hard to see. Shaman tremors also blocks the lightning quite a bit. I do like Kauket! We have to constantly keep moving. It's fun.
In terms of general feedback, as fun as it is to do the bosses and earn sands quickly, I personally feel this event is way too much. >.< There's the green bounties, the caliphs, the pyra 3, the ladder, and the dailies.
A pharaoh spawning every hour. Caliphs every 20 minutes. Ladder and pyra, which both need groups. So finding groups for those, plus, trying to get bounties which die way before you get there.
As someone who tries to get some sands for alts, too, it's overwhelming, even just trying to do the pharaohs once a day. Those trying to do some juggling may struggle. Vale was a lot more manageable, and it found a nice balance in terms of having the fairy bounties, dailies, and the ladder.
I find only the jokes quest and the quest to kill enemies outside the pyramid worthwhile. The joke quest is a bit tedious since it's hard to tell at a glance who you have to talk to and sometimes you have to talk to all of the NPCs. The gathering quest isn't really worth it, and the fossil version of it in particular can be very annoying if the RNG isn't on your side. The backpack quest is more trouble than it's worth. The guardian killing quest is worthwhile only if you happen to be doing something else in the pyramid anyway or maybe if you have run out of bounties to fight.
Is the layout of the pyramid interesting? Is it too confusing?
If I've seen it all, it's fine. I very much dislike that it's placed on the same map and in the same general locations as the stuff outside the pyramid, though. It's difficult to know what's inside the pyramid and what's outside. They really ought to be in entirely different positions, most likely by extending the map westward for the pyramid portion.
Are the Guardians (basic mobs) in the pyramid too hard? Too easy?
Much, much too hard. Just getting unlucky enough to happen to be in their spawn location when they spawn has killed me. That stun thing they do ought to be axed and their numbers strike me as excessive. I'm able to just barely kill a group of 3 of them on my own if I have the chance to strike first and be as strategic as possible. Even that sometimes isn't enough.
Are the bosses (Ruhak, Toses, and Imhotep) too hard? Too easy? Are they interesting?
I honestly have no clue which bosses are named what, but all the bosses are fine. I didn't notice any distinction between them other than how much general strength they have, and that one boss in the pyramid stuns so often that I accidentally pulled aggro because the tank was having trouble hitting them. I think that boss (don't remember the name) stunning too much is the only problem I have with any of the bosses, but I didn't find any of the bosses particularly interesting.
On another note that wasn't explicitly asked about: it seems to me that the "vial of the sands" rewards are excessively low. It gives an impression of the vial of the sands rewards and the expensive items that can be bought with them as being designed primarily as a pipeline to push players into premium purchases. That makes me feel less inclined to spend all that much time in the event zone. This is compounded by the fact that the event feels kind of generic and boring overall; if my impressions are right, it's mostly just fighting some bosses that all look like mummies and sometimes are called caliphs or pharaohs. It has the feel of generic content for people who have run out of interesting things to do, which hasn't happened for me at this point. Overall result is that going to do things at the event zone is mostly an afterthought for me, and mostly just consists of doing the two daily missions that give 25 vials and maybe fighting a mummy or two.
I also feel that the event is poorly explained. I still don't really know what the "ladder" everyone is talking about is, I never would have guessed that the random easy bosses scattered through the desert are the "mummies", and I still have no idea how long the event is going to run, which only adds to the demotivation I discussed above. It would be very helpful if items that are set to disappear at the end of the event said explicitly when that is, if there was a glossary or FAQ somewhere discussing the basics and general terminology of the event, and if bosses that count as "mummies" were explicitly marked as such.