He's pretty much exactly what we need and genuinely an improvement on Lukaku, so however it "makes us look", we have to do it, in my view. I'm pretty sure almost no one in the league is turning down half a season of diego costa up top. It's the same length as a January - May loan and gives us more time so sort out a permanent solution.
That said, whether this works out really is dependent on how arsed he is to play his best for us, seeing as he's not playing for a move, arsed about staying first choice here, or trying to stay at Chelsea. It could end up being a massive disappointment if he treats it like a holiday.