Just changed all 4 tyres from XM2 to J5 for my 15 years old second car. After 1K, here is the verdict:

Pros:
- Comfort ride even on rough surface (better than XM2)
- Very good wet grip (better than XM2)
- Decent dry grip (similar to XM2)
- Short braking distance (feel better than XM2, maybe it is still new)

Cons:
- Very noisy (noise level same as the wear out XM2)
- Rolling Resistance (feel that XM2 is better)

Conclusion: J5 is a good choice if you are looking for budget tyre but do not want to compromise on safety. The only trade off is the noise.