They basically are giving you an interest free, two day loan.

That can be a trap for anyone who starts to rely on that, because at some point they aren't getting it two days "early", they are simply getting it on time, but two days ahead of when their company sends it because they will have become accustomed to the earlier pay date and their finances will reflect it. So it may be a good feature in a pinch and as a one off, but ultimately it just means you will probably get used to payday being that two days "early".