Just flew Air India ORD-LHR on Sunday (in Y) - and was positively surprised.

I basically flew with AI just because I had never flown with them before, and accidentally (after a few beers I thought it was a great idea) ended booking on their web-site during my previous trip to the US in November. At least the price was good (247.10USD all-in one-way), although that benefit was diluted by the fact that I had to buy connecting SK flights LHR-ARN-HEL and that I actually had to fly from YOW to get to ORD.

The experience
(i) Check-in: arrived ca. 100min before departure, had to queue maybe 10-15min. No problems whatsoever.
(ii) Boarding: AI started boarding from the back of the a/c, and the process was relatively smooth.
(iii) Cabin: 747-400, a bit worn but clean enough. I had heard horror stories about toilets, but I didn't find anything to complain about. Seat-pitch was good, on par with UA Y+, I'd say - certainly much better than my outbound flight CDG-ORD w/ AF.
(iv) Food: Food was ok - the curry was a bit bland, but I had eaten at ORD so no worries there. Having finished my 3 bottles of water I made several trips to the galley to get more water - however, I'm not sure about alcohol on their flights (they do have some available).
(v) Entertainment: Some music channels and big bulkhead screens. This time they were showing some sitcoms and a film featuring Tom Green. I chose to read and chat with my seatmate instead.
(vi) On-time performance: arrived at LHR 30min ahead of schedule. This had been my major worry as I needed to connect, but it worked out perfectly.

I was positively surprised by my experience with Air India, and I wouldn't hesitate to fly with them again (provided I could afford possible delays). I believe my next trips across the Atlantic will be with European/American carriers, although I'm tempted to give PIA a try at some point.

Conclusion: if the price is good, and FRA is your final destination (i.e. no connecting flights), Air India might be a good option.