Yes and No.

Yes because Jonas was a great actor and no one could replace him as acting Robin and if someone did it would spoil the series.

No because I want to see what happens to the gang after Robin dies.

I think the show still had a little potential, even without Jonas. After introducing the Archer storyline I think they could have carried it at least for one more season.
But on the other hand, the show didn't have much to tell. It was hard enough without Marian and now without Guy.

yes, all my favorite characters (isabella marian allan and guy) are dead so is robin so whats the point in continuing the series.

I prefer a serie that ends, than a serie that continues without bright ideas... such as The OC, for example. After the third serie the storyline becomes awful. I prefer a short but great storyline than a long, boring, absurd one.
It's just my opinion, of course.

I didn't even want too watch the last episode. After Allan died I was down. But I only watch it too see if Allan would do what Marian did is season 1. I was hopeing Allan would come back too life. But he didn't:( My Robin Hood ended when Allan died.