I play a level 58 bard so I am by no means the final say on this topic, but I think my opinion is worth stating. If we are talking strictly a solo basis, in a dungeon, you'll die often. Some of your major setbacks with regards to straight up melee with a bard are: 1)no double attack or triple attack but you can compensate with some of your DD songs, 2) most mobs bash so if you're the only target for them, they will interrupt your offensive songs often(ie dots, mez, etc), and 3) no root type spell.
Don't take these as complaints, becuase bards can do alot of things, but a non-kiting solo career doesn't seem to be one of them. In a dungeon environment, a bard will be an incredible enhancement to your group if you have a good tank that can keep a good portion of the aggro.
I also have a lvl 50 ranger so I can make some comparison. I would say a ranger could solo a tad better indoors because of the ability to root and range attack with your bow.
-Farcy