I really like Swell so far. At 0.75% per year it is more expensive than most robo-advisors but Swell helps you purchase many individual stocks instead of ETFs so it is more expensive for them to provide their service. You would also have to pay the fee of the underlying ETFs if you choose to use something like Wealthfront or Betterment while Swell's fee is inclusive of all costs.
Their stock picks are broken into categories such as Renewable Energy, Green Tech and Zero Waste. You have the option of choosing how you want to distribute your investments into these categories but I stuck with the default mix which is an equal distribution in each category.
I will wait a bit before I can compare Swell's performance to other robo-advisors but it has returned similar to other robo-advisors so far.
I'm uncertain whether or not investing in socially responsible companies can actually make an impact so it's sort of a feel-good thing I'm trying for now. Apparently, investing in socially responsible companies can lead to higher returns because they tend to be at the cutting edge of innovation but that remains to be seen.
I'll probably keep some money in Swell but it hasn't become my main investment platform.