I played a little bit of Point Lookout last night, just enough to get oriented to the area and the general vibe. Not very far into the plot yet... just looking around. The environment design and atmosphere is well-done, I think. It feels a little less "plot on rails" than the other DLC's, but we'll see how that goes.
I agree it's probably better as a side-quest for medium level characters, but I think it still works if you're willing to roleplay it at a higher level, and go very light on armor and weapons. Light armor makes you more vulnerable even at level 25.
I'm having fun fooling around with melee weapons too, which I never really did in the main campaign or other DLC's. Staying simple there too, with either a shovel, baseball bat, or that fancy sword from the Chinese general at the end of the Anchorage DLC. The sword looks good with my leather armor and confederate cap. Yee haw!
Still no idea if it's a good bang for buck. I'm trying to stretch it out and play in small doses instead of just running through it, so it may take a few days to finish.