During my trial of assisted modelling, I've enjoyed how well guided the process is, however, I've come across one area for improvement that would help those (including myself) overcome any hurdles when getting started.
When I ran my first model, I was presented with an error stating that certain fields had classes in the validation dataset that were not present in the Training dataset.
Upon investigation (and the Alteryx Community!) I discovered that this was due to a step in the One Hot Encoding tool.
Basically, the Default setting is for all fields to be set to error under the step for dealing with values not present in the training dataset, but there is an option to ignore these scenarios.
Add an additional step to Assisted Modelling that gives the user the option to Ignore / Error as they see fit.
If this were to be implemented then it would remove the only barrier I could find in Assisted Modelling.
Hope this is useful and happy to provide further context / details if needed.