TD&H
The problem seems to be with AOL. AIS advise that they have had a number of AOL users today reporting problems. Nothing has changed on the AIS site, it's the AOL browser upgrade that seems to be the culprit.
In answer to your question, I probably have some contact with AIS on a weekly basis.
It's an interesting situation. Most pilots take a very parochial view without realising the briefing service is provided as part of the UK's obligations under the International Convention on Civil Aviation and has to conform to the standards laid down by ICAO. An understanding of the standards framework within which it operates is a great help. Unfortunately ICAO does not publish its documentation on the Web but the two main docments are Annex 15 to the Convention and ICAO Document 8126, The Aeronautical Infrormation Services Manual.
As you know, it's a free service, so the scope for spending money on alterations or the provision of services over and above what is required by the Convention is limited. Of course if we were all to pay for it that might be different!
Austria uses the same software for a paid for service. You can see their implementation
here and also have a free trial. As you will see they also include the Flight Plan Filing option.
In my experience the site does a very good job, providing the user takes the trouble to understand how it works.
Mike