First, we have a brand new record for the lowest number of points that a challenge could grant: 250 points. Previous record was 350 points, so this didn't just beat the old record, but destroyed it.

I've confirmed on PTS that, just like the endeavor, this only works with manual picking, not with force-lock. So, thanks for punishing everyone who leveled up their legerdemain! And 30?! That's a lot and coupled with having to manually pick, this is another one that just feels way too grindy.
[Screenshot shows a doubled challenge] Here's one to make the lockpicking one above seem even more ridiculous in comparison: You can open 5 chests with lockpicking--or with force lock! And you'll get 375 points instead of 450 points. So, 83% fewer locks to defeat for 17% fewer points. Plus the option to defeat locks the easy way. This treasure chest challenge is fine. Very desirable, even. The lockpicking one above is just plain horrible in comparison.
[Screenshot shows a doubled challenge] Here's another bad one, 525 points for 15 safeboxes. These are much more rare than treasure chests, and yet we need 3x as many to fully complete the challenge?! You get 16% more points than treasure chests... even though you need to open 3x more things that are more rare than treasure chests and that carry more risk than treasure chests. These should be 3x1, not 3x5!

You need to complete 12 dynamic encounters for this. Incursions are probably the closest thing to compare this to, and incursions are 6x1, not 4x3. And incursions are more readily available, as they are in every major zone and there's always one that's active. And DEs are more time-consuming. So, let's summarize: more time-consuming, less readily available, and you need to do twice as many? WTF?
[Screenshot shows a doubled challenge] And another point in the "dynamic encounters need too many" column, if you compare against incursions, not only do you need half the number as dynamic encounters, but you have the option to progress twice as fast if you do Glenumbra Dolmens.

When we had guild dailies in the endeavors system, it was complete 1 for a daily. So even if you were to do a guild daily endeavor for every day of the week, it'd still be 7. Here, we need 18. This means someone dutifully doing the full MG/FG/UD daily set for 6 out of 7 days a week. In case you're wondering why people say that the new tome challenges are way more annoying and grindy than the endeavors that they replaced, here's an exhibit for you:

Ah, yes, the tooltip for the previous guild dailies did say that you get bonus credit for TG dailies. But how does that stack up against a challenge for actual TG dailies? See, this one for heists is way, way better and goes to show just how out of whack the guild dailies one is.
[Screenshot shows a doubled challenge] This is effectively pickpocket 75 items, which is just gross. Compare this with Blade of Woe, which is 6x5. Pickpocketing is more time-consuming, since you need to wait for that "green" chance, and it requires leveling a skill line if you want to succeed. Also, it would be nice for there to be a way to abandon challenges. You cannot reroll a challenge after claiming some of the points from it, but if you've pickpocketed 40 times and decided that you've don't more pickpocketing than you care to do, then that challenge will remain, taking up one of the limited challenge slots.
[Screenshot shows a doubled challenge] 20 quests of a specific type for a weekly. Grindy. Excessive. Etc. Why are these so much worse than the Heists?

And for people interested in how quickly reroll costs ramp up...
Editorial note: Some of these challenges were doubled. This doubling happens at the end of the season, when the bonus pages have been unlocked, so the doubling makes sense in that context. There was commentary surrounding the doubling that was made in ignorance of this context, and that commentary has been edited out, and screenshots that show doubled figures are marked as such. The current comments in this post are based on non-doubled amounts.