This is kind of a "dead horse" thing as stated above.
But then, if you aren't informed...you don't know...
I had my '01 since they first came out. I loved it, it gave me 40K great miles. They are relatively comfy, but it would definitely be time to get off of it by the time the tank was empty (~200 miles). The mileage is WAY better on the GenI's...I usually got 42-45mpg without trying to be in "eco-mode" with the right wrist. Gotten over 50mpg on trips, and some tanks were under the 40mpg mark if I was in one of those moods for that long. I never had trouble with it...until I started thinking I wanted to trade up (different story). Some people are kind of "nostalgic", and like the carbs...others are for modernization.
I wouldn't say the GenII is down on power, according to the mags they have a couple hp less, but that can be easily remedied (power commander, and other common mods to extract more hp from it...and it IS IN that engine!) To me it feels as fast if not a bit quicker....but that could be the digital speedo. The new ones don't get the mileage like the 1st-Gen bikes do, I have been averaging 34-ish mpg in 3K+ miles. Comfort level is about the same with the stock seat as the GenI...it is time to unflatten the ass after a tank, which is more like 140-150 miles now, due to the smaller tank on the new ones.
Looks are subjective...some like old better than new, and vice-versa. I think both have their ups and downs. I'm not a big fan of the little slit in the windscreen on the new gen, which lets more dirt and dust up along the inside (where I can only reach by removing the F-ing thing!). The old one looked like it was trying to please everyone...sporty, touring, everyday, commuter...instead of just making it's own statement. Yamaha's colors on the new ones are nice...but I like my gear to go along, and the dark blue doesn't flow with all my medium blue gear...
Your brother is just jealous...because he KNOWS yours is faster, and it can get WAY faster than what it is now with a little work that he cannot equal.