Do you mean Home Assistant? (Their URL is HASS.io) or something else?
If you mean home assistant, I think the most common integration would be to use MQTT and the most common reason for that would be to get SmartThings access to zigbee devices and other protocols that are not supported by home assistant. On the home assistant side, you would be getting local operation and back up and restore utilities. But it’s going to require a strong technical background to put it together.
Although the people on the home assistant side tend to argue that their solution is easier than writing rules in SmartThings, I don’t think that’s objectively true, particularly with the advent of Webcore, which is essentially a scripting language for SmartThings.
Best use I have found for a Raspberry Pi is to build a RetroPie classic gaming system.
I also use a Raspberry Pi to run Homebridge with the SmartThings Plugin. This provides Homekit capabilities for iOS users. I don’t really need it, but since I had a Raspberry Pi laying around, I figured why not.
I truly prefer the simplicity of the Arduino / ESP8266 micro-controllers. No operating system to deal with. Simple to write code for. Here is my project/platform for using these micro-controllers with SmartThings.
I am a Samsung fan, I have a Galaxy Edge, 4 Smart TVs and I’m working on getting the vacuum and upgrading some of my major appliances next.
The smartthings security sensors in my opinion are (a) some of the best, (b) cheaply priced and (3) have more sensor data than some others.
There really isn’t a reliable solution for Zigbee devices right now on the home assistant platform, so a hub is usually the preferred method. (By this i mean a reliable usb dongle that accepts a large variety of devices)
There are a few devices that don’t fully integrate into home assistant but have third-party solutions that do work with smartthings.