It's a lil' bit costly way to gain a specific type of action once per game, because this card does only that. Have a look at the Shortcut. You gain the same amount of value from those two cards, but Shortcut is 0xp 0 resource and can be used on any player creating opportunity for some wild shenanigans. On the other "Hand" -Eye Coordination special effect could be sth like avoiding attacks of opportunity. Sometimes. In very rare and strange occasions it might be a thing you need. So as long as you have access to pool whenever you start to think about this card, just remember Shortcut. In fact guardians have more much nicer action compression cards like Safeguard, Ever Vigilant, Geared Up or even Galvanize, so if you find use for Galvanize and you don't care for its exhaustion effect and it's possibility to play events than maybe it's a card for you.

I updated foobar's excellent jsfiddle from their Olive McBride (0) review to include Olive McBride (2) as well. You can play around with the chaos bag to see specific values. However, to summarize:

• Olive McBride (0)'s weakness was that she was often not worth it. If you were up by 2-4 on a skill test, which is common on Standard difficulty, Olive's ability would often lower your chance of success. The same is also true if you were even (up 0) on a skill test and didn't have Father Mateo's auto success on Elder Sign to save you.
• Olive McBride (2) does not have that weakness. Using her ability raises your chance of success for almost any chaos bag and skill value, sometimes up to 10-20% more.

Even without considering token-hunting shenanigans (Elder Sign for Father Mateo, Skulls for Jim Culver, Bless/Curse in general), Olive McBride is a considerable upgrade just for passing skill tests, and should be prioritized accordingly.

That is a terrible rulling. Deny existence shouldn't negate Diana's weakness. The point of ignore vs cancel is that if a card has multiple bad effects you simply ignore one of them and do all the rest. It wasn't written that way to wiggle out of a signature weakness such as this. If you want to use bad templating as an excuse to give yourself an easier time that's fine, you can play the game however you want. But it's pretty obvious this isn't what they had in mind with Deny Existence and simply forgot to to add "or ignored" to the weakness.

From the above official answers:

Q: Luke plays Read the Signs to investigate a connecting location with a ready, unengaged Young Deep One. Does he take 1 horror? (I think no, because he is considered to be engaged with enemy, but there is no timing point of engagement.) A: Luke playing Read the Signs on a connecting location would not cause him to engage Young Deep One or take 1 horror.

Ouch. Although technically correct, this answer fails to address the fact that you would still incur 1 damage and 1 horror in the form of an opportunity attack from young deep one. Failing to include this information in an official answer just leads to confusion and could cause players to incorrectly assume they can play this card and other events without possible attacks of opportunity. They wouldn’t get the 1 horror since there is no engagement timing point to take it, but they are still considered engaged with young deep one and therefore will incur the opportunity attack.

After some testing, Dr. Charles West III is... inconsistent.

There are two main benefits to the doctor. The first is that he gives an additional hand slot, which can only be used for tools. This means you're trading an ally slot for a tool slot, and which encounters the usual problems of cards that take up slots for slots - you need extra actions to fill up those slots. Now, Seekers will effectively have a free hand slot, since most can justify running Magnifying Glass to fill it, and there are other useful tools that could be use - but that still needs you to spend more resources and actions to fill the slot, which is never great when your actions can always go towards investigating.

Second, on some successful investigates, he can exhaust to deal damage - but only on investigates that only succeed on 1s and 3s. This is two levels of specific - first, you need to succeed by 1 and 3. This is doable, but rather inconsistent - sure, you could use Steady-Handed to improve your odds, but it's hardly a guarantee, and Steady-Handed (and its other synergy, Chemistry Set) already encourages you to succeed by a certain amount. Second, this requires you to be at a location which has an enemy that can take one more damage.

There are very specific cases where he can be useful, but they require some fairly niche builds. If not for the differing classes, I'd be hard-pressed to find a case where you'd want to use him over Alice Luxley. His Science trait is the only notable one, and that's of limited use - he's not even Miskatonic, so he won't be getting any Miskatonic Archaeology Funding And with so many good Seeker allies available as is, you'd want a pretty specific place to fit the doctor in.