This happened to me in the summer with DH. Bought him an iPad for his 50th and he never took it out of the box. My DS 17 has just had it for Christmas! C'est la vie, no bother, you can't get it right all of the time. At least your DH feels able to tell you the truth without facing armageddon.
My mil got my Fil an iPad last Xmas and he got her a camera. He wasn't fond of the iPad and she made no bones of telling h he got the wrong camera. Made for a bad feeling on Xmas day. In the end he got used to the iPad and she got the right camera so all good... Maybe he just isn't used to using the tablet yet? If it is just the wrong one I would let him return and exchange for something else as he would always be thinking the other is better.