Rehab: Overall, it's aiight. I'd either use a brighter piano, or bring the moodier piano more to the front.

Now and Then: A nice groove. I'd use a different voice on the piano riff that comes in at about the 8th measure--a synth, perhaps?

Alchemy: I like the sample, but I'd find a way to chop it and preserve its pacing, rather than just pitch bending it. The piano and distorted guitar/synth are great, and really complement the mood. Good stuff.
------------------
Tony "Keynote" Sebro
www.myspace.com/beatsbykeynote