I absolutely LOVE Last Night on Earth (I have it and most of the expansions). With that said, it very much depends on what you and your gaming group likes.
I'll start with the cons... Fighting is based around rolling dice and both zombie and hero players are at the mercy of their respective decks to draw what they need to stop the other side from reaching their goal. So if luck being a pretty strong factor in your games is a problem, you may want to avoid. That doesn't mean skill and planning isn't rewarded or that there aren't interesting choices to be made, though. Both certainly happen, though people might disagree on whether it happens enough. I definitely think it does for what the game is trying to be.
For the pros... Flying Frog Production games are all about theme and LNoE is dripping with it. The components are also of really great quality. If you're the type that likes games that feel like they're telling a story as you play, this is a great choice. If replayability is a concern, then you should be pretty happy with the modular game board, different heroes available, and scenario choices. A few extra official scenarios are available online for free. When you get sick of all that, there's plenty of expansions that add even more of everything, including different mechanics you can mix and match. And if you really wanted to, you could create your own custom scenarios, heroes, and rules, or go to the board game geek community and look at all the stuff other people are sharing.
Also, there are actually two standalone games: Last Night on Earth and LNoE: Timber Peak. Timber Peak is an expansion that has everything you need to play it standalone. The only thing you'd be missing out on is the soundtrack (yes, FFP incorporates atmospheric music with their games). Of course, the soundtrack isn't amazing but can be fun to pop in your first plathrough at the very least. Timber Peak adds a leveling system and some other stuff (spreading fire!) that hadn't been seen yet in the series. I only played TP once, so I can't say whether to get it over the original. I think most would, though I'm concerned about the zombie side being weakened (again, may have just been that one game).
But yeah... hopefully that rant helped. I can definitely answer more about it if you're still on the fence.