There has always been something unique about the concept of the original Rough Riders. This strange anachronism of riding a horse into battle alongside laser and plasma weapons and giant mechanical constructs is quite telling about the 40K universe.
I know these are not the best painted examples in the world but I was a bit scared doing the horses with another 100 Bretonnians sitting on the shelf waiting for a lick of paint.
Gaming wise I always liked to field these, even if they have been over costed ever since Second Edition. I just like the idea of them rolling across the battlefield and throwing back a squad of power armoured monstrosities!