Your brother is exaggerating, of course, but there is a grain of truth to what he says (aside from the idiotic Harley comparison). The 7R is no longer competitive on the track, though a really good rider will be able to hang with today's liter bikes on a tight circuit. I suppose that is true of a really good rider on most any bike.
The 7R is a porky bitch compared to more recent sportbikes. Not exactly Goldwing territory, but at ~515lbs wet they are heavier than many of the bikes on the road today. Turning radius is best described as "barge-like" as well, so low-speed maneuvering can be tricky. Most sportbikes are not terribly friendly at parking lot speeds, though, so not much difference there. It's much more noticeable when you are trying to jockey the bike around in a driveway or garage. Once you are moving the weight is not that much of an issue and actually proves beneficial to the stability of the bike in corners.
Power is on par with today's 600's, though the extra cubes of the 7R allow a much wider spread of torque - exactly what you need on the street. In fact, the 7R makes as much torque as last year's GSXR750 up to 9500rpm. You don't have to be constantly running through the gears to make decent progress. Nobody runs around the streets at 12,000rpm all day long, so peak numbers can be misleading with a street bike. Engine internals are heavier than more modern bikes, so the 7R is a bit of a slow revver. Head-shake is nonexistent.
Commuting / Road Trips
I've been commuting on a 7R for a long time and travel quite a bit as well. In stop-n-go traffic no bike is fun, and the 7R's extra weight and heavy clutch pull make it worse. The last few years my commute has become 20 minutes of back roads where the bike really shines. Throw a tailbag on and you can carry anything you might need for the day, and be able to stop for a few things on the way home.
As far as road trips, it's a mixed bag. The riding position is pure race rep compared to today's sportbikes. You are leaning forward with your knees high. On the freeway, this position can get uncomfortable after a while so I frequently stretch my legs. You get some funny looks from other drivers as you let one or both legs hang freely at 75mph, but it does help. 3-4 hours of highway speeds will have you noticing a buzzing through the foot pegs that can become annoying. Back roads are much more fun anyway, so unless I really need to make time, I'll avoid the highways.
That said, the seat is wide and comfortable and you'll need fuel often enough that you'll have plenty of opportunities to get off the bike and relax a bit. Windblast with a stock screen hits you in the chest which helps to support your upper body. I found most double-bubble screens direct bugs right onto my visor, but a really high one like an Airblade works reasonably well.
There's plenty to like about the ZX-7R. They are solidly built and easy to maintain, one of the best-looking bikes ever and Kawasaki got the weight distribution right on the money. The front end stability is legendary, even today. You just need to be realistic about what you are getting into. This is not a bike for everyone. Depending on your needs, skill set and even your size, it may or may not be a good fit. Only you can make that determination.