It depends how you do it. The most beneficial, in my opinion, is not to write it down until it's finished. You gain a strong concept of tone, fron whoever you're doing, as well as working on your inner ear, training it to instinctively identify a pitch, and helping your rhythm. Lifting licks off records also helps your playing, and phrasing. The other method, usually what I use for harder solos, is to work out a bit, then write it down. What you gain here is an etude of the player you've done, so you can analyse their lines and phrasing. When you transcribe the harmony, you can see how they treat individual chords. Writing the solo down also really helps your reading of rhythms. Each approach has it's benfits, and gives certain areas a lift. Enjoy your transcribing. PS a good starting point for transcribers is to do the solos from Jim Snidero's "Jazz Conception" books- after learning it, and writing them down, compare your solo to what the book says, and instant correction!

Scott- I think I may have a different opinion on this than most people. I think one of the most important thing to be gained from transcribing has to do with tonal concept. In other words learning how to apply the sound you hear in your head to the saxophone. When I first started college, I wanted to sound like Dexter Gordon, but I could never get that fat sound of his. I had listened to his recordings 1000's of times, but still I couldn't get it. Finally, I started transcribing some Dexter solos and by concentrating hard on matching his tone while I was transcribing I came across a revelation!!! I never knew that I needed to put that much air through the horn. It seemed that after I got used to it, the more air I put through the sax (with control) the fatter my sound was. It was completely the opposite of what my logical brain was telling me at the time. I would have thought that the louder you blew, the brighter your sound would be. But, alas, that was not the case!!! By transcribing solos, I quickly lost that typical "high schoolish" flabby sound and quickly developed a full fat "Dexterish" sound. Cheers, MarkO