If it was featured in ZeroPunctuation, you should probably not buy it. There are exceptions, though.
Well, he kinda said in the review that SR4 reached the peak of sillyness which makes it a good game. And in his Top/Flops 5 of 2013 he nearly gave the top 1 to SR4. Considering I enjoyed the 3rd one... I would probably have fun with it.
Question is: is it worth 20€ to me?