My world has quite a few new races, and while some players don't care, some do, and that's all you really need for it to matter.
The biggest problems I've seen is that hosts create races that bring nothing new to the table and expect players to embrace them. Why should they bother?
Tybral (the most popular) - picture a combination between a gorrilla and an armadillo. The Tybral use to be the nobility of a continent spanning empire, hundreds of years ago before the Upheavel. The Tybral were not popular among their subjects, and since the collapse of the empire they are generally run out of towns, have settlements of any significant size forceable broken up, scorned, insulted, and jailed or even killed at the slightest provocation. Those Tybral who still retained some honour and pride soon found themselves removed from the equation, and those that survive do so by staying quite, laying low, and simply trying to be productive members of society.
Saarpen - If a naga could be considered a human crossed with a python, a Saarpen would be a halfling crossed with a viper. Agile, quick, and with a powerful venom, they are also weak, abrasive, and have a fairly twisted sense of humour. They get along well with other Saarpen, and have a tendency to litter the slums of larger cities engaged in various manners of illegal activity. They tend to be strongly individualistic and have a general contempt for authority, but they are also capable of being quite discrete and subtle about the ways they will show it. While a bit dimmer than most of the other races, and not inclined in the slightest towards book learning, they are quite smart when it comes to matters of figuring out how to get ahead in whatever organization they find themselves.
Chrantlar - picture a combination between a praying mantis, a moth, and a millipede, and you've got a good idea of these guys. They generally keep to themselves, are fairly hard workers but averse to large numbers of their own people, which make them feel uncomfortable. Renowned for their rather vicious tempers, though their agility, dexterity, resistance to injury and amazing work ethic make them sought after laborers wherever they roam, and capable adventurers as well.
Hursk - distant relatives of the Chrantlar, beyond certain similarities in appearance, they are not much alike. More beetlelike than their siblings, Hrusk are incredibly social creatures, whether in their own sizeable societies or with other races. They have a natural gift for languages. As children they have the ability to fly (something they lose as they increase in size). They are not terribly quick or agile, but their thick exoskeleton and fur give them a natural resistance to damage. They make good administrators and organizers, and are generally well liked - they have a reputation for spreading rumours and being terrible at keeping secrets.