Arguably the best (tie-up) Lego kit outside of the Ultimate Collection Millennium Falcon. Definitely a labor of love and I had no qualms forking over the requested price (especially since the limited-edition "mini" Batmobile kit that it came with is no slouch either -- Lego should offer it as a separate purchase if they haven't already; it would sell amazingly well).
Im a huge LEGO fan and I admit that I just bought the mini-Batmobile seperately (well it was a gift, but still). Haven't built it yet but I'm very glad to have it. Just wish it had the Burton Batman figure, might buy it seperately someday.
While I never built the UCS Falcon myself, I always felt like sets like it or the UCS Hogwarts (which I do own) are more impressive for their scope than their actual builds.
Saturn V is probably my favorite overall LEGO set for how cool it's build is, and how impressive it is in the end (seperatable multistage engines, tiny lander build, lots of printed pieces, etc.).
Wall-E is a close second. Not the biggest set or the most complicated build, but it looks fantastic.
Ninjago City is probably one of the most fun BIG sets since it has so many super creative smaller builds (crab BBQ, ATM, moving sushi bar, etc) in addition to being an impressive overall set in terms of how big it is.