We needed Pienaar. We were in the CL and still in the hunt for a CL spot in the league, we needed some backup to Lennon and to some extent Bale as Harry doesn't seem to trust Kranjcar in big games, I don't blame him. He could also provide backup for VdV and possibly in central midfield in a 4-5-1. He was the kind of hard working utility player we needed, and he also seemed to have enough quality about him to make a difference. He was experienced, knew the league and was available for a fairly small fee.
We had to pay him as much as we did since he most likely already had solid wages at Everton and Chelsea were after him as well and they were probably offering him more than we did.
Harry played him plenty when we first signed him, didn't seem to be a player he had pushed onto him.
It just didn't work out, for whatever reasons.