The main problem with the Today's Specials is more often then not, the offers are basically nearly pointless or overpriced. Lets take the various Skystealer Crystals for example...even playing casually like I do on my alts, I have amassed thousands upon thousands of them. There's no reason to spend 400 NCoin (or 5 USD effectively) on them when a couple days of effort would suffice. They could be removed from Today's Specials and nothing changes for 99% of the playerbase.
Things like the Secret Safe also are a really, really bad deal for a different reason: 100g is not worth 400 NCoin. Neither is 300g or even 1000g, when you could achieve better cost effectiveness with F9's Currency Exchange. The current going rate seems to be averaging around 1g to 0.3 NCoin, meaning 10g is 3 NCoin, 100g is 30, and 1000 is worth 300 NCoin. It is more cost effective to simply buy the gold off of F9, though this may shift in the future if the exchange rate reaches 1:0.4 or higher.
I will provide more feedback over the coming days as I cannot recall all of the Today Special rotations, but those two things I feel are horrible deals currently. But to balance out the negative feedback, here is some at minimum neutral feedback...
While I haven't purchased them, 400 NCoin for 500,000 Unity Rep is...maybe okay? It could be better, but that is an entire day of maximum possible effort right there, and the classic argument of time vs money can apply here. Likewise, 10 million Hongmoon Experience being worth 300 does not strike me as immensely horrific either and tends to be just shy of what I'd get in a single day if I do 'everything': dailies, 3x spectral shrine runs, login bonuses, ect.