I have one with adjustable height. If the grass is tall I set it to the highest level, then I cut again at a shorter level. My gas mower use to cut with more precision, the reel mower tends to be less even but inconsequentially. If you're super into your lawn, this might bother you, my neighbor is one of those who has to have the lines from his gas mower all perfect, he can't handle any imperfections.
I also have mown the grass at 6 AM and 11 PM; it was dark, I was home for a few hours before leaving again for a week. I can mow at any time, gas mowers have noise bylaws to follow. In addition, they're safer, my reel mower doesn't throw rocks at kids and cant chop your hand if you stick it in the blades (kids are crazy, I've seen numerous children with mower amputations). From an environmental view the VOC's from gas mowers are horrendous, you're stuck breathing that in with gas.
Overall my favorite part is the tranquility of mowing. Get a drink holder attached and its very peaceful walking around. I like listening to the birds sing while I mow. Big bonus, it doesn't stir up dust/grass pollen, way easier for people with allergies.