Yeah man! Very clean mix, nice groove. Good to see some real R&B on the clinic. Once in a while someone will post music like this, but usually the instruments are electronic.
Great bass sound. Good vocal for the genre, but it could use some support. It sounds like you have some kind of harmony vox going on, but they are low and indistinct. You could use some backing vocals that are strong and present, preferably female.
I'll echo what everybody else has said about the guitars. I'm a fan of understated guitars, but there is a sweet spot. It sounds to me like you were having trouble getting that lead guitar to blend, so you mixed it down. I can understand why. That spikey strat tone (good tone reminiscent of Steely Dan, but dominant), might be the source of your blending troubles. That guitar is going to call attention to itself, leaving you no choice but to turn it way down.
I'd suggest two things. First, if you are interested in doing more tracking, a smooth, understated rhythm guitar that can sit in your mix at a consistent level would be a good addition. Second, try automating that Steely Dan guitar. Find those nice fills that work with your vocals, and bring them up a bit. The rest can be mixed down or out.
The solo must come up.