it's also great being able to change tempo, style, key, etc. iReal Pro is used by every pro musician i know around town

I get very frustrated with cats on the stage who rely too much on the iReal Pro. If they don't know the melody, then they easily get lost when, for instance, an intro or other section is skipped (such as when the singer re-enters on the bridge after solos), and in general their comping tends to not be aware of how the melody fits in with the changes. At least when reading a leadsheet, readers know how the melody and harmony interact and can better play fills around the melody.

For good and for bad. Its strengths are available to all and its gaps (melody!) and quirks (lack of variation) impact everyone’s development.

I'm a jazz bassist, 61, and first saw a Real Book 43 years ago.

There were, and are, always a few hard-liners who look down on reading tunes from a book, on the bandstand. They're not necessarily the oldest, or best players, or have the best reasons. Whatever. Most of the gigs that I've played, fake books were accepted. There are similar debates in most musical styles.

Roughly 20 years ago, I decided to stop bringing fake books to gigs. I quickly discovered that I didn't need them. For one thing, the "local repertoire" wasn't vast. For another, it exercised my ability to pick up tunes by ear. I see more of what's around me, and interact more with the band and audience, because the music stand isn't there. Today, I have a bunch of stuff on an Android tablet that I keep in my bag just in case, but rarely bring it out. The tablet also contains stuff for bands that use written arrangements, such as a 19-piece jazz ensemble.

I personally think the inaccuracies are immaterial. Most players will never encounter a situation where the ur-text is important. The players I've known who mostly learned by ear don't play 100% accurate changes.

I'm not a full time pro, but am often called as a sub, so I've observed many levels of bands. I've formed the opinion that the fake books do in fact detract from performances. I hate "dead air" between tunes while the players flip through their books (or thumb through their phones) to choose what tune to play next. It's a little bit cringe when a good player who should know a beginner tune, reads it. Flipping through the books may be just a habit. Plus, dependence on the books limits the repertoire in weird ways. Real Book has practically become its own genre. Remember, the "contemporary" tunes in the RB are 50+ years old.

The problem is that gigs and jam sessions are no longer frequent enough to afford players a chance of learning tunes by ear. The books aren't going away. Bandleaders can figure out how to deliver a better performance. Send out a set list in advance. Let people listen to the tunes that they're unfamiliar with. If needed, they can transcribe them. I do that a lot when asked for a popular tune that doesn't have available sheet music, such as most country-western.

I feel like that commenter was a little harsh with that statement - I will say however that it has caught some flak as a source of truth. There are quite a few standards (principally, original jazz compositions by jazz musicians that have now become "standards", this probably isn't as much a problem for true "Great American Songbook" standards since those were always notated), that were transcribed incorrectly in original versions of real/fake books. To the point that many younger generation players are playing incorrect heads and/or changes to tunes since they learn it from the book rather than by ear. Not even that, but often they are just straight wrong, or dumbed down versions of the changes.

Anybody who's worked with it for any length of time knows that the charts contained are good enough for jam session purposes but either contain inaccuracies when compared to the canonical versions of songs or may have been based on the "wrong" (according to some) canonical versions. Working this out means developing your ears and listening both to the original recordings and to the musicians you're playing with in a given situation. Many people end up in a place where they're just using their ears and memory to skip the book entirely, which in some situations is an essential skill.

Most level-headed people I think regard the book as a useful tool, a step in the growth journey. As egos and insecurities enter the mix you'll occasionally find somebody who'll proclaim that the Real Book is purely a crutch and you should start and end with the ear-training bits or you're "doing it wrong".

The Real Book is an excellent resource for what it is. However since it is the primary book of jazz, it can have too much of an influence. The Real Book has a limited number of songs and entire subgenres of jazz are not represented. The structure of the songs is relatively narrow. Songs are rarely added.