IOTA is being called the 3rd generation of cryptocurrencies. It has fast transaction and no fee's at all. It's also quantum computing proof so the quantum computer won't endanger it's existence. So it looks like this cryptocurrency does not have a lot of the negative aspects that could endanger the future of many other cryptocurencies.
Tangle:
Another very important aspect is that IOTA does not use the blockchain. Blockchain transactions will be verified and saved in a "database" called the blockchain. The blockchain is like a teacher that reviews your homework and gives it a grade. Tangle is like a smarter teacher that tells his students to review each other's homework to safe a lot of time and work.
If you send a transaction you will automatically verify someone else his transaction. In return someone else verifies your transaction when they send a transaction. This is the reason why there are no fee's. Blocks don't have to be mined, calculated or verified by minders or stakers.
IOT:
IOTA has it's purpose as a cryptocurrency but does not have the advanced features of creating smart contracts or to run DAPPS. IOTA does market themselfs are a platform for the internet of things to be used on. So machines will also be able to connect and use IOTA. So machines will also be able to trade and connect with eachother.
Quantum computing:
The bitcoin network's encryption could be cracked by a quantum computer because these computers have the calculating ability to crack the ecryption. So they could brute force someone's bitcoin wallet to steal funds etc.. But it will still take a long time before we get to that point. Bitcoin is going to have to be upgraded to be able to stay safe from quantum computing. IOTA however is already quantum proof and this is why it's called a 3rd generation cryptocurrency.
Coin supply:
IOTA has a fixed supply of IOTA coins. The total amount is massive: 2,779,530,283,277,761.
This is why exchanges don't calculate the price by one IOTA but by a million. They call this one Mega IOTA. So if you look at coinmarketcap.com you would think that one IOTA is worth $0.302173. But this is actually the price of one million IOTA's. So one mega IOTA costs $0.302173. So keep that in mind when buying IOTA's in the open market.