Bards are almost always welcome in a group.  However, be warned that they do not make a great solo class.  While they are not as good at any particular thing as any of the specialized classes, they do a little of everything.  They can cast, tank and heal as circumstances dictate.  No other class gets the variety of spells and skills that the bard gets.  Bards can also cast forever since they don't use up mana when they sing.  Such ablilties as heal, mana regeneration, find corpse, accelerated travel and group invisibility make a bard invaluable group members.  While the bard only does one thing at a time, he does it real well.  And a good bard is able to twist as many as three songs at a time to get multiple effects.  If you are a social person who likes meeting new people, the bard may be for you.  If you like to go off on your own a lot or are shy about travelling with strangers, you may want to think twice about playing a bard.  I once saw a pretty well reasoned argument on a message board that the most powerful group you could put together would be 6 bards.