OK, it's more "real" than an IOU I hand you, because I know that in order to issue their IOU they actually had to deposit an equivalent amount of cash with the Bank of England, but it's not legal tender -- while in practice pretty much anyone should be comfortable using it as a medium of exchange, the only _guaranteed_ use of a Scottish note is to exchange it with the issuer for a Bank of England note (or, in Scotland, coins), which you can then proceed to use to pay your taxes or other bills because they _are_ legal tender (value limits apply to specific denominations south of the border, you need to use pound coins north of the border).
But yes, in practice, real money. Just don't try telling anyone they've _got_ to accept it, because there's no such obligation.