I think all of these things are true:
We'd have been worse off without Viktor this season.
We've been lucky he's been so available.
He has scored some important goals for us.
He has also been a complete non entity in many matches.
He appears to lack either the technique, touch, pace or the physicality to really prosper on a regular basis as our centre forward.
Finally, he is not suited to our style of football.
I think he's a bit of a donkey really - I see Gooners walking around in their Gyokeres shirts and genuinely feel a bit bad for them.