The U30 has the most reflective screen of any TV I've ever seen.
Granted that a showroom isn't a suitable environment in which to judge a TV, however, in that arena the U30 is a mirror.
Your Gran will doubtless want to watch tv with the lights on at night. The location of the lamps may cause reflection issues.
This could be avoided by opting for the next model up the Panasonic range... the S30. It's £450 but worth stretching the budget. It also has good reviews from AVForums, TrustedReviews, etc.
The U30 hasn't been reviewed, so it's performance in objective terms is 'unproven'.