Yeah, it's worth it. I liked it a lot. Just don't expect a 3rd-person world filled with run-of-the-mill inventory item puzzles.
It's different. Gets more difficult after the introductory puzzles. Lots of info to digest for your little grey cells.
But don't take my word for it, if there's one thing I've learned from game forums it's that one man's treat is another man's poison.
Spycraft is not rare, you can buy it on ebay or gametz for just a few bucks. If you want a brand new boxed copy, pay a bit more and go to CDaccess.com.