'Point Lookout' is the 2nd best piece of DLC for Fallout 3.
Whether 'Point Lookout' is a must buy is the real question. In my opinion, that would be a "yes". Even though there isn't much in the way of game changing gear or weapons. They didn't raise the level cap again. There aren't many new perks. But playing through this DLC makes me think this is what 'The Pitt' should have been: a great way to extend the original game while telling a new story in a brand new area.
The story of 'Point Lookout' is an interesting one. You take a ferry to the area and will instantly realize you are in a much different environment then the Capital Wasteland. 'Point Lookout' is based in a swamp-like area of Maryland. There is a main plot line involving a pissed-off Ghoul who has an interesting background and after helping him defend his mansion from attackers, he gives you several quests to do. I can't give away too much about the plot without spoiling things, but this is a much more interesting plot line than the one found in 'The Pitt'.
The real treat here is the side-quests, of which there are several, including one where you have to investigate what happened to a Chinese spy. This is, easily, the most interesting quest in any of the DLC and is a real treat to play through. There are a few others, including one that has you searching for a very evil book.
Where 'Point Lookout' falters is in the lack of any great new weapons or gear. The double-barreled shotgun is nice, but you have to reload after every shot so it's not very practical to use. There is a rifle that is slightly better than the standard 'Hunting Rifle' found in the original game, but it's not that great. In fact, if you have the Abraham Lincoln rifle, you won't have any need for the new gun at all. You do get a very handy new energy weapon at the end of the main quest, but that's about it.
And a word of warning to people who are not around level 30......'Point Lookout' is WAY tougher than the original game or any DLC that followed. I had a very high level character who was best at combat and I ran into a couple times where I almost died. The enemies are much tougher, deal much more damage, and are very numerous. I welcomed the extra challenge, as I thought the other DLC was too easy for my character. I just thought I would throw it out there in case people decide to play 'Point Lookout' earlier than they should.
I am very happy with this add-on and would recommend it to any fan of the original game. It's light on new weapons, perks, etc. But if you are looking for a big, brand new area to explore, interesting quests, and some challenging combat, then 'Point Lookout' will be right up your alley.