Where the rubber hits the road, so to speak.

Frets should be level, and they usually aren't. That's a bummer.
The good news is that your frets can be made level. Sometimes the existing frets can be leveled just fine. Other times, the frets are pulled, the fretboard gets planed, new frets go in and get leveled. Anyway, I do all that, and I like it.
Good fretwork provides immediate and noticeable benefits. That's the reason I like it: I can hand you the guitar and watch you have more fun with it than you were having before. Nothing is cooler than that.
Here's the part where I tell you why fretwork from this operation is better. Whenever possible (that's almost always), I do my fretwork in the Erlewine Neck Jig. It's a really smart invention that holds your instrument in the same position it was in under string tension. Necks can move a lot under tension, creating ripples, bumps, and twists. Doing fretwork without this type of equipment will provide less fantastic results, because all of those irregularities can disappear when the neck is relaxed. I don't like surprises. My customers don't like surprises. That's why I do fretwork under tension. It takes more time, the equipment costs more, and the results are better.

Note for the Plek fans: Pleks are great, and can do the job when they're operated by a competent individual. That's as far as we'll get into it.