Brakes are weak on the GR / GX's but twin pot front calipers from the GPX are a direct swap and as said GTO items can be fitted. I find the GPX twin pots pretty decent on the road, not sure how well they hold up on track.
Suspension isn't to hard for UK roads, I run std shocks with eibach springs which are stiffer than standard and the ride soaks up bumps well. Id rate it above my mk1 MX5 with koni sports kit all round.
Steering feel compared to the MX5 is not great, leagues apart, same with the gear change and the car does feel heavier and more wollowy compared but its not that bad, expected as it is a bigger and heavier car -- it does handle and stick to the road very well though.
Usually see people slating them for being heavy as they look it but they are actually quite light for their size at around 1170kg for a prefaclift GPX (around 1200 across the range give or take a few 10kg's) so p/w ratio is actully not that bad if its still got all of its 197 horses after all these years which alot don't.
The engine as far as i know is like most V6's of the time and made of aluminium (not sure if its just the heads or not) so not really that heavy compared to cast iron turbo or petrol diesels. Similar to the Mazda K series V6's which seem to be made out to be mega heavy when they aren't that bad.
The sound with decat / mongoose catback and an itg or HKS filter is fantastic, especially when the MIVEC kicks in, really gives the engine a nice character, mega mega loud though so does sound alot faster than it is and you get the classic burbly V6 rumble at low revs under load.
Engine also loves to rev although the gearing feels quite long so I think this is why it doesnt feel very powerful, its very smooth and linear and as already said it needs to be revved very veryyyyyyyyy hard for it to go anywhere fast. Especialy compared with almost anything moderately fast coming with masses of turbo torque at low rpms nowadays.
I'd say they are fairly quick for the class of car they were designed to slot into. A good MIVEC manual is around 16-17 0-100mph so about the same as focus ST's (standard, similar power to weight) etc and 1/4 mile can see mid to high 14's so again similar / slightly slower compared to your ITR's focus ST etc etc. It just requires a different driving style so its easy to see how they could be caught out on motorways or any modern hot hatch with a few mods such as remap etc.
The other reason I think they are known for being ultra slow is the looks as said placing it into supra / gto / rx7 / 300zx / skyline class of cars in peoples minds when it is most definitely not! And the biggest reason I think they are generalised as slow is that all trim levels and specs look pretty much identical, so when someone comes across a 1.8GS with 125hp or a tip / auto they think all FTO's must be like that.
There are a few of some japanese racing vids on youtube of them compared to INT SI, 180sx, MR2, m3 plus others and it does fair pretty well compared to them.
Edit - here it is http://www.youtube.com/watch?v=iTiXnCFT9cY
Heres some very rough times I've seen banded about on some of the owners clubs of tsukuba time attack: (I don't know just how accurate it is or not take it with a heavy pinch of salt)
fto gpx 1.10.80
fto version r 1.10.50
integra type r 1.10.20
tt 3.2v6 1.13.80
r32 golf 1.13.80
civic type r 1.11.90
astra vxr 1.12.90
Rust is common on the suspension turrets, especially under the main fusebox and roof rust on pre faclift cars mainly darker colours such as black.
Climate control units can also fail but a 2nd hand one can be had for as little as £5 and fitting is a 10 minute job.
Driver seat bolster material also wears easily.
Headlights can have sun damage where it looks like they are peeling but some cutting compound + wet and dry sorts this.
Rocker covers leaking.
Drop links and steering rack gaitors needing replaced usually pop up on the forums quite a bit.
Need a decent alignment or they eat tyres.
Sticky rear calipers.
Just wish I'd bought one years ago as they are getting on a bit now and getting rough around the edges...