OK, so here is the feedback.
Generally, I like the start. I do wish there were more options and I anticipate they will be added as time allows.
First, I really like how the General tab shows the linked email addresses. I have some clients that like to use one email account as a catch all for a bunch of aliases. Sometimes, it gets hard to track them down in ISPConfig3. Having this displayed to the end user in one spot is useful in my opinion.
The password changer worked great. For an administrator, I really like the ability for users to change their passwords. It takes a lot of pressure off of me to do that and frees me up to do other important things. I would like to see the ability (either in Roundcube or ISPConfig3) for an email to request a password reset should they forget their password. I don't know how the workflow would happen yet, but at least they could initiate the process. Additionally, I am coming from Squirrelmail. The Squirrelmail Change Password plugin could be configured to force users to change their password after a fixed time interval. I liked that option as an administrator.
Autoreply worked as advertised and mostly as expected. When I enabled the Autoreply and sent a test message from a Hotmail account, I received an automatic response nearly immediately. When I disabled the Autoreply and sent a test message from a Hotmail account, I received an automatic response nearly immediately. I waited a bit and then sent another test message. An automatic response was not received. Is there a ISPConfig3 cron job on an interval that must run before the autoresponse settings take effect? If so, perhaps my first test after disabling was performed too quickly before that cron job had updated the system settings.
I tested the Junk settings. My test account had the Priority setting at 5. When I changed it to 6 in Roundcube, I saw the email account added to the Spam filter Users list with the priority set to 6. So it would appear it worked. Prior to the change in Roundcube, only the domain was listed in the ISPConfig3 Spam filter Users list. However, I have posted many times here seeking clarification on the Spam filter settings. I don't understand how the Priority setting is applied.
On my wish list of features, I would like to see users have the ability to white/black list settings for the Spam filter. I haven't thought it through yet, but some advanced users should have the ability to change their Spam filter policy setting. I don't know how you would limit which users would have the capability and which ones wouldn't.