Rear-facing seating is very common, and not a problem for most. The only time you're likely to notice anything "strange" is during periods of acceleration or deceleration, which will be when you're pulling into/out of a station, but you quickly get used to it. When traveling with someone else, I much prefer this style of seating, as it's more private than sitting across a table from a couple of strangers, and you both have direct aisle access.