I have the book and there are a few worthwhile things in it but overall it was a disappointment. For comments on it go to AZ Billiards and do a Search for Upscale One Pocket and you will get a couple of pages of comments under that title.
Upscale One Pocket deserves a few more kudos than it is getting here, in my opinion (IMO).
For those folks like me that never had access to "action rooms" full of chatty knowing con men (now, bench held by Freddy and Grady) back when young and weren't players in the Johnston City tournaments in '62 (when I was 2yrs old and had trouble aiming brown stubby nipple=milk with mouth back then) it may seem a boring read, old hat, simple, common sense, obvious, etc. But for a learning one-pocket newbie in an area short of 1P action to watch, it could be caviar, elixir, milk of the Gods, a great new intellectual challenge on par with chess and the gateway towards the grandest pocket billiards game blend of all to play. One pocket calls players of a certain caliber or gumption to test their mettle in the one game of pocket billiards overall strength (Judgment! Defense! Patience!).
Koehler's drills are useful, as are his science bits, and the general strategy guidelines.While not overtly fabulous and on the whole very defensive natured, but then neither must every shot by a beginner be compared to one successfully executed by a Billy, Buddy, Cliff, Efren, Grady, Freddy, or Shannon to pull off. Watch the 5 recommended accustat videos here (only $170 or so) and see greatness in action, defense overall being a very wise course if your offense has holes in it.
Teaching a good 9-ball player one-pocket ideas on defense while leaving only jacked up shots against the rail 2" from his pocket teaches TORTURE and the resulting message WHY SHOULD I BOTHER WITH THIS TRICK GAME WHEN I CAN WIN NOW AT MY GAME OF EXCELLENCE? The message sending may be $$ now for you but just Wait till I get old and these current farts die. THEN I'm maybe interested in winning some one pocket games. (You may rightfully suspect I also have a masterful almost 10yr-old daughter playing me like a recorder, over here, parentwise. On the music side she has mastered Edelwiess and is moving on to piano chords from her friends, such envy I hold)
If your goal is to develop new players, my first advice is let them win the first games, real cheap. Goodwill, encouragement, bread on the water, etc.
The worst move I ever pulled (for development of the sports) in my local pool room was beating the SS 9ball owner (me A-) in one-pocket, me being a low A or high B player with some knowledge of the game (forever I am branded as an A banker ONLY, but generally a B+ player overall) Unfortunately, I made the same mistake tempting him into a short 14.1 game, I played, won, now he won't risk his reputation again on 14.1 and nothing but 9-ball set race matches, or ring games (which I hate, are slow=out of stroke, have stronger players, little chance of winning at, I decline unless there are 2 weaker players than me in the mix. lockmeister? Hate to lose, know better players when I see them, why contribute?.)
Though he owns the room and I play almost every day there, he remembers the time he thought he owned me on the bet of race to 8 with 2 on the wire and even up one-pocket (he figured to break even winning the 9ball maybe losing the 1P match) when I played well and got ahead in the 9ball match, he gave up and wouldn't finish the 1P part of the match.
I will leave it there... but sometimes leaving loser monetarily plants a seed for the future... as in Billy Incardona's story of Jersey Red, making the tough double-kiss bank into his hole, then deliberately losing on the inside-english winning bank straight into his opponents hole. Today, who knows, the Jersey Kid may yet be taking it down.
Bottom line: Koehler's book Upscale One Pocket is a start in the right direction, as is any Eddie Robbin's book Winning One Pocket or Shots Moves Strategies, or almost any Grady Mathews tape, or Billy Incardona's Accu-stat tape on proper One-pocket strategy, or accustat tapes with good commentary from real matches, or learning from what you see in real action rooms. I am all for developing, on the less painful side, newer one-pocket players.