My mate owned my Celica from new for 11 years before buying a new GT-86. He loved the Celica and could not find anything to replace it with until the GT-86 came out.
Parked next to one another the cars are very similar in proportion. The Celica can definitely give it a run for it's money in the looks department, with just a few details making it show it's age.
He still misses a lot of things about the Celica - for one, it's way more practical considering the cars are the same size.
Performance wise they're similar, with the GT-86 having more low down but torque lacking that banzai scream at the top end. The Celica engine has more character - as long as you thrash it of course ;-) They may be slow compared to some modern cars, but I rarely want for more to be honest, and are still way faster then most cars on the road.
Having said that, the GT-86 is all about handling and balance. In the right conditions the RWD can be great fun, and more accessible than on other similar cars. I got to take part in a GT-86 track day at Oulton park (only as a passenger unfortunately) and all the drivers had a ball. On the other hand, in wintry conditions you may be best off leaving it at home!
I'd love one. It's great to know there's something out there to replace my Celica eventually. With the current depreciation I might even be able to afford one one day.
Pics from the track day:
Old vs new: