I have tried the stop over function, sometimes it doesn't work because the fare rules are not loaded, even when they do stop at the stop over point, you then have to call a consolidator to book.
The simple multistop function is missing, even when the journey is very simple, eg LGW
website doesn't allow OLCI if the flight number is a codeshare.
The offer of an upgrade feature is great, especially if you want to treat yourself on the return part of your journey.
I have seen Club Europe upgrade fees as low as £1 for some off peak flights.
They should also have front page news headlines, if more people now about flight changes the better IMHO.
They are investing a lot in IT
, to save costs and improve customer satisfaction, I think we will see more clever features on their website.