I'm in a similar situation as you. I doing Europe to Australia in March, and I was looking to book a flight with Thai, but as I finally choose my flight there was no more availability and was force to choose to travel via India on Vistara & Air India or Air India alone. I was reluctant to book with Air India, but didn't have much of a choice.

I have found this video to give a pretty fair view of the product and some of the issues to mentioned
Good luck!