The Honda Rebel is a 250cc cruiser for beginners. It is not slow! It is capable of cruising at Interstate speed, even with a passenger, if you so choose to do so. Most of the people that say they're "slow" are sport-bike nuts or people who have never ridden one. The Rebel is a perfect starter bike, great for around-town riding, commuting to school or work, etc. Similar bikes are the Yamaha 250 V-Star, Kawasaki Eliminator (125cc or 250cc), and Suzuki GZ250. If you want a cruiser-style, THESE are the best bikes to start on.
FYI, I ride bikes over 1100cc daily, but still have a 250cc Rebel that I enjoy riding around town and short trips because of the excellent gas mileage (75+), and it will haul myself (170lbs) plus a 140lb passenger all day long!
Riding and repairing motorcycles for 40-yrs