I am starting FO2 over with a melee/unarmed character. I've never tried this before, I am usually a ranged character or a mix. Is melee viable/fun for FO2? Thanks.

It's quite fun really!
I've played a melee character a couple of times, and its quite important to have high strength, agility and endurance. Luck also helps if you can get those criticals.
You'll find that you tend to have to run away a lot at times (esp. in open wasteland), because you need to get up close and personal to make an impact.
There are plenty of weapons available, and the key is getting the Super Sledge, it's my favourite weapon. :)
Early game will be made more easy, it tends to be mid-late game that is harder. Pick the right perks though, and you'll be okay. (Bonus move is often quite good, to help you get close).

I though I wouldn't like it at first, BBUUUTTTT... Its a LOT more fun. Things seem weak at first but stick with it, atleast until you can beat deathclaws to death. lol

yeah, unarmed is the best. I started a 16 year old girl, and ended up kicking the final boss to death in the eyes. Epic win. If you do it, I reccomend you go to the san francisco chinatown, to the docks area with the shop on the boat,(haven't been there in a while), and steal a power fist, then run. I got one early in the game like that. lol

Once you get Slayer, you're god.
And don't forget to buy/steal:
Mega Power Fist (San Francisco) - Unarmed
Super Sledge (New Reno, San Francisco) - Melee

The thing that sucks about melee, at least early in the game, is when people run away. So you use all your AP catching up to them, and you can't get a hit in.

Great idea. :D
I normally play ranged so I just aim at people's heads.

Playing Fallout 3 at the moment, and I'm quite disappointed there aren't any groin shots or shooting of eyeballs.
Also fairly sure if you tried being a melee char in FO3, you'd have real trouble with raiders and supermutants.

Not as much as you think. You have to be careful early that much is true but I made myself a Kharn the Betrayer Character and he was kicking ass and taking names. I had to think out attacks on random people a little more but I got the job done.

Or you can wait while a NPC (Cassidy, for example) blow the head of the foe.