After being introduced to ARK by the delegate 
DPOS - Earn Passive Income Through Staking
The first interesting aspect of ARK is the delegated proof of stake, similar to Steem with the 21 witnesses. ARK however uses 51 delegates who run public servers with the ARK code and get rewarded for that in new ARK. You can vote for one single delegate, which costs 1 ARK and can earn you a share of the rewards, depending on what that delegate is offering. This is basically a passive income stream for holding the coin.
The idea of staking is also less energy hungry than mining with proof of work. My personal view on that is that both systems have their advantages but it is good that many new coins use the DPOS system like STEEM, BitShares, EOS, LISK and ARK. I heard that BitCoin already needs as much energy as whole Nigeria. And ARK allows to bridge both systems anyway which brings me to the next point.
SmartBridges - Connecting Blockchains With Each Other
This is where it really gets intersting: ARK uses encoded listerners or code snippets to enable transactions between different blockchains. This makes ARK an intermediary that allows for seamingless interaction between the supported coins. You can technically send ARK directly from the ARK wallet into for example an Ethereum wallet via a third party service like Changelly that would act as an encoded listener to scan for SmartBridge transactions.
ACES - Aces Contract Execution Services
ARK offers tools for developers to allow ARK to make contact with these other blockchains in form of smart contracts or actions like uploading files, executing blockchain code and communicate with IoT hardware. This approach can take load off the other chains and allows for an interconnectivity of the free market with room for everyone.
ACES is the community project developing the first integrations.
ARK Makes Blockchains Talk To Each Other
To communicate across blockchains is a huge advantage for the quickly growing crypto market which is currently a whole bunch of disconnected island economies. ARK is creating the bridge for all of them and basically makes users stay within ARK and never even touching the used blockchains or their usual applications. This is a smart move and super interesting for a coin like Steem that is used by many people and could use easy access to more common payment coins like BTC, LTC and ETH.
I think ARK is an interesting project that has a great usecase. The technical aspect is pretty complicated and I had to read into it before I got the full concept. But it is pretty powerful what ARK has created so far and the community is active and supportive. Connectivity is important and ARK is specialized on that. I will have to learn more about ARK as this was merely a first look at its functionality.