My experience is that it fits in the bins. Just fits with wheels inwards, (literally JUST fits), and plenty of space if put in sideways but why do that and take up more room than needed?
It is quite practical and not an issue - however if not travelling on BA then not all airlines accept the same size and I have had to check it with a couple even though I went outbound from the UK and it still fits in the overheads on the planes. As you can imagine flying back from a German airport it WILL be noticed and you WILL have to check it if the cabin size back on that airline is smaller!
I think most people are fine with the size. It's not stupidly large. It is only when you get people with clearly oversized baggage that will only fit in sideways and they are travelling in ET but stuffing their bags above your head in CE that there is an issue. Of course I say this when I mostly travel in CE and if one makes sure to board in Group 1 then space is not an issue!