We raised 2 jersey steers last year for the first time. It takes them forever to pack on the pounds compared to any of the beef breeds. The resulting meat was very tasty and had a decent amount of marbling. It did however have a lighter yellowish shade to the meat than I was used to. Did a few calculations on the feed, milk replacer, vet bills, etc stuck into them and we figured that it cost us about $2.34 per pound to raise those buggers (not including any of the labor). Beef breeds on the other hand have a much higher feed to gain conversion and are ready for market sooner. If you even look at the meat section in the supermarket you can tell a beef from a holstein carcass just by looking at the ribeyes. The beef will have a round ribeye and the dairy breeds will have an oblong one.
The guy that rents out our main pasture has a mix of charlais, herford, simmental, and angus cows heifers and a gigantic gelbvieh bull out there. Some of the charlais cross old cows are kind of onery right after calving. The meanest bulls I've ever encountered have always been holsteins though.