Woah...
Love all the effects and sounds... really nice dark sound.
You really know how to create an atmosphere, which is crucial to the Ambient genre.
One thing that could maybe use some improvement on (and even then, it's not that bad as is) is the drums. They're just a tad bit too generic and plain sounding. The reverb on them sounds great, but maybe they could use some variation or a little complication.
This song makes me thing of NIN's "Something I Can Never Have," or another of their earlier works. It's not so much about the melodies, but the effects and sounds have a similar quality to them; the drums are slightly reminiscent as well because I believe a drum machine was used on several of their tracks.
Another area that could be worked on is the overall structure of the song. It all sounds great, but there's not really any basic form to it. Just different parts put together. I feel like it could go on a lot longer too.
I'm going to assume it's supposed to be short because it's an intro (as stated in the title). I hope that it really is only an intro because I'd love to hear it go on.
Great stuff here. Keep it up.
P.S. I listened to "To The Grave." Some great vocals. A lot of potential there; you've got talent.