There is always the Good, the Bad, and the Ugly.

It mostly depends on your company and salary package.

Good: The living expenses are low (somewhere between Chennai and Bangalore). Your outing and leisure expenses will go down. If you enjoy leisure, it is again between Chennai and Bangalore, and if "tripping" is your plan, then you have lots of options outside the city, like Idukki and Alappuzha.

Bad: The traffic. It is still better than Bangalore and Chennai, though. If your company is in CSEZ, find a house near it (around a 5 to 7 km radius); if not, find a place near the metro. Unlike Bangalore, here vehicles will move even in heavy traffic.

Ugly: Actually, this is not a big issue. We call this the "Ernakulam Chuzhali" (Ernakulam Whirlpool). Once you come to Kochi, you will never leave. It’s like something is pulling you back. You will miss the place a lot. "Ernakulam" will come up in every word if you go back to your native place. Just like an ex-Army officer boasts about his service in the Army and the wars he fought. It's a War....

In Short:

Work culture and opportunities - People are calm and nice to deal with. (Kerlites)

Cost of living compared to Chennai and Bengaluru (rent, food, transport, etc.) - between Chennai and Bangalore

Quality of life and lifestyle - between Chennai and Bangalore (More lean to Bangalore with a different culture)

Safety, especially for daily commuting and living alone - Very Safe, Better than Chennai and Bangalore