I've bought 2,3,4 and 5, originally bought 4 first because of the rhythmic ideas and odd meter stuff, that really helped me with playing in 5 as well as odd grouping, it was really big as for opening that stuff up for me now that I think about it.
I then bought 3 which is the harmony part which is great also and with my semi hollow and polytone/delay/reverb sound I was getting that kurt,Lage,Kreisberg sound and I was really in to it, lot of ideas with replacing the 3rd with the 4th in chords.
Next I got part 5 because I had got through and worked on the 5 feel stuff and odd groupings and part 5 was all about playing in 7, how to turn tunes into 5 or 7, metric modulation/poly rhythm ideas and gear and talking section.
The last one I got was part 2 but I was starting to get over it a little it was about melody/scales ideas.
The ideas in part 2 were much like the sound you hear from Kurt and other New York guys, Lage Lund always came to mind with the sound I was hearing and Kreisberg, ideas in 5ths, new arpeggios and augmented ideas.
Now that I write about part 2 I might get back into it, bought it about a month or 2 ago but started to feel I was letting those lessons do all my thinking for me so gave it a break.
I bought them one at a time as I really wanted to learn this modern jazz style, spent about a month or 2 just on the rhythmic one (part 4) before I bought the next and kinda did the same with that one.
It's semi heavy stuff, nothing you can't handle but there is a LOT in each video so I reckon even buy one and work your way through.
I would watch the whole thing first (little over an hour long) and see what was in there and then work my way through.
I can say the biggest one and the one I learnt the most from as I feel it was my weakest point was the rhythmic one (part 4) lots of good ideas and really took my ideas to another level as I could use the odd note groupings and poly rhythm ideas on lines or ideas I already had.
Just thought I'd mention it.
Only thing I thought would be cool if they had some kind of buy 2 for $40 or when you buy one you get $5 off the next one as it often took me a while to decide to spend $30 on them, they are great for the money but if your into buying a lot of them and even from other teachers and rack up 10 videos from that site it would be cool to be rewarded with a small discount after you buy a couple.