IOTA is the worst of all worlds
I don't like the use of a centralized validator, and would not trust any coin that uses one.
I think there is a place for centralized technologies: Chaumian banks. It is a matter of trade-offs. Digicash had excellent privacy and fungibility, but was centralized; Bitcoin is decentralized, but lacks Digicashs privacy and fungibility on the blockchain layer. (Lightning mostly solves this problem in a different way.) Centralized solutions also have high performance and low overhead, generally. I would not like a Chaumian/Digicash-style bank. Digicash does not require the issuing bank to confirm the identity of transaction participants, but there is nothing preventing a bank from collecting information about transaction participants as a condition of signing new certificates. There is also the risk that the bank will become insolvent, or will issue unbacked certificates, or will simply run away with customer deposits.
Lighting is very similar to Digicash, except without the risks related to having a central issuing authority. There do appear to be some problems with it in practice.
Whereas IOTA has none of these advantages. It promises to be a Bitcoin-style cryptocurrency, but better than Bitcoinwhich it is not!
In the practical terms which matter to the average user, I think that IOTA is really a Paypal-style solution, but with much higher overhead and, I think, lower security than Paypaland it is a financially unstable altcoin which makes an even worse investment than government-issued fiat currency. Why would anybody want this? It combines the worst of all worlds!
Indeed, if I had an exclusive choice between IOTA and Paypal, the answer is easy: Paypal. I say that as a Bitcoin maximalist who holds almost all his own money in Bitcoin.
I find the idea of a DAG and having transaction fees that are too small for the average user to measure (a small amount of POW per tx) interesting. The IOTA foundation appears to have a goal of eventually removing their central authority in favor of a decentralized authority who validates transactions, however I am unsure if this is possible in light of the fact that transactions are (virtually) free.
To be fair to IOTA, this is a single instance of reversing transactions in a case of alleged large scale theft, there is a 'slippery slope' argument, but this is not worse than what PayPal does every day. PayPal will routinely reverse transactions, block access to funds, and will blacklist individuals/entities who are doing things that PayPal does not like, even if not against any rules/regulations that PayPal has published. There is no slippery slope argument with PayPal because they are already at the end/bottom of the slope.