Good things- nice one. Nice big screen. Sharp clear photos. Amazing sound clarity. Go for 64 Gb version, you can pack quite a lot of songs and movies. It works like a phablet in android family. I gave my iPad mini to my little daughter once I got 6s plus.
Bad things- screen is big and tends to consume power faster. Keeping screen brightness lower saves battery.
Apple enjoy sending updates and consume your day data limits fast. Best is to take updates in a single go during night times.
Budget stretching can't be avoided.Put a Mercury cover till few more 6s plus appears in office. Everyone will want to check yours(!).