Dobby's life could be viewed from quite a few different perspectives.
If you could get Lucius Malfoy's opinion on it (without him hexing the Bludger out of you), he'd open his mouth and say, "That traitor was worthless and a fool!" He'd go on to say something particularly nasty about meeting the same sticky ends as some other folks, but before he could you would go on and hex the Malfoy swagger out of him.
If you could get Hermione Granger's opinion on it (she'd be speaking to you with her nose buried deep in a textbook, of course) she would open her mouth, revealing the not-so-large-but-still-oh-so-large front teeth, and say, "Oh, that poor little dear. At least he was free for the remainder of his life. I am on a mission, you see, to free more sweet elves like just like him-" But before she could finish, you would already have Apparated somewhere far, far away.
If you could get Ron Weasley's opinion on it (or perhaps, any Weasley) he would open his mouth, scattering the freckles on his cheeks, and say, "Bloody hell! Blimey! Bloody hell! Blimey, a house-elf, why, we've never had one of those, but then again we never had an Aeroplane or a fellytone either-" And before he could continue, you'd have tuned him out already.
If you could get Lord Voldemort's opinion it-well, sorry, I'm afraid he's dead, so you can't.
If you could get the opinion of Dobby himself (he'd be beaming at you with those large twinkly eyes of his) he'd lift his giant elf-nose and say, "Sir/madam no need to worry, sir or madam. Dobby had a great life; Dobby made friends with the goodest wizard of them all: Sir Harry Potter himself! Dobby loved collecting socks and he had lots of them-splendid, oh yes, splendid, sir or ma'am. Dobby had a feeling Harry Potter liked Dobby and Harry Potter is always Dobby's hero, so Dobby could not be more grateful. Dobby lived a great purpose, Dobby died a free elf. What more can Dobby ask for, sir or ma'am?" By this time, you'd be trying to hide the tears in your eyes from Dobby, who would then politely offer you a tissue. But you refuse and you move on, for you know you must.
If you could get the opinion of Harry Potter about Dobby's life (he would be staring blankly with those bright green Lily eyes of his, but in them you would also be able to spot the kindness) he would mutter, "Dobby was and will always be a hero to the Wizarding World. By saving my friends and myself from Malfoy Manor, Dobby indirectly saved us all. Dobby was the bravest, smartest, and kindest house-elf a wizard could've known." And before you know it, you're missing Dobby terribly again, as much as Hedwig, Sirius, and Fred.
But then again, they all died for the same great cause: They died trying to protect Harry. They died trying to make the world better for the living. They did not deserve to die. However, their legends live on. And as Dumbledore once told Harry, "Do not pity the dead. Pity the living."
Indeed.