In terms of technical ability I don't think many would disagree that Lee is one of the best mashup producers there is. It's perfectly demonstrated in this track.
He effortlessly turns Dragonette's vocals into a harmonic reggae / chillout combination. Pay close attention to just how well three different songs all work and play off one another.
The guitar solo during the middle eight is timed to perfection - no easy feat when your using multi-tracks that have not been timed to a conventional click track.
At the start of December, we'll be launching the annual Mashstix search for the top 20 mashups of 2010, expect to see Lee there (he won it in 2009!).
Cons:
There really isnt any. I do wonder why you are not remixing for a living. I know some remix producers that are signed, who don't have your ability.