Languages seem to be Site123’s thing. Not only is the editor available in more than 20 of them (including languages such as Turkish, Arabic, Romanian), they also feature multilingual websites. The editor is relatively restrictive, a bit like GoDaddy’s GoCentral. If you just want to get the website job done, without becoming too creative this might suffice. But you have to be aware that their template system can be a bit on the restrictive side.
Some WordPress plugins conflicted with our design.  When we installed some of the tools / plugins, they broke some of the custom features that our developer built. So we had to pay our developer to re-configure our website to make things work. When you’re piecing together tools that are built by different developers, it’s not surprising that some of them won’t work well together. It’s just part of the process, and it was frustrating for us as that added to our mental burden.