You want a handheld PC so you can play your library on the couch, on flights, or anywhere else without being chained to a desk. Buy the right spec with plenty of storage the first time so you do not have to upgrade again next year.
Summer is the sweet spot for these sales because manufacturers often drop prices to clear inventory right before autumn release cycles hit. That means you can frequently grab last year's model at a steep discount while getting nearly identical real-world performance.
That 0% intro period is a hard deadline, not free money, so if any balance is left when those 15 months run out, you will get hit with standard interest on the original amount.