How strong is the Nimzo-Larsen Attack ?

Possibly helpful:

The Nimzo-Larsen Attack: Move by Move (2013)

https://web.archive.org/web/20140627052905/http://www.chesscafe.com/text/hansen175.pdf

"Many opening monographs have enthusiastic titles of the form Winning with the... and invite the reader to ingest some marvellous system or other and rack up points - either by encyclopaedic knowledge of main lines or the methodical application of simple strategies. So let us make it clear, first of all, that White has no advantage in the Nimzo-Larsen. The lines in ECO, for example, conclude mostly in '=' (equal) or 'unclear', with just a few '+=' (White stands slightly better) and even these '+=' seem optimistic. Nor is the Nimzo-Larsen a 'system' opening in which the first moves are played parrot-fashion regardless of the replies. There are system-like elements in some variations - the plan Bb5, Ne5, f2-f4 in the reversed Nimzo-Indian (Chapter 4) for instance - but more often White (and Black) can do just about anything. Anyone who likes to win their games in the opening should therefore look elsewhere." - Byron Jacobs & Jonathan Tait (2001) in Nimzo-Larsen Attack

https://web.archive.org/web/20140626223637/http://www.chesscafe.com/text/hansen27.pdf

I use the 1.Nf3 move order just to reach a decent middlegame against opponents I know are big on theory but struggle when dont have much tactical stuff to analyse.   Basically What Jacobs said

It's a fascinating opening for sure. It avoids the endless trees and variations and branches of a lot of openings, doesn't run into tactical nightmares and minefields like a lot of the double e openings, and allows you safe, confident development and position. It's been one of my favorites for a long time, even through I still need to learn a lot of ways not to mess up. 

very good

Against a strong enough player, every opening I feel like there are pitfalls and small mistakes that can ruin the game for me. Those sorts of things where you almost flinch because you worry every move he makes is going to ruin you. Especially against a computer. 

The Nimzo Larsen Attack is the one and only opening I have played where that shot just never comes. They just never do find a way to bust you up. You never come out of it in trouble. It is the safest, least stressful opening I have ever used. Now yes, you aren't going to come out of the gates and take his head off with it. But at the cost of the aggression, you purchase safety and security. 

I have been familiar with the old Nimzo-Indian Attack before Larsen got attached. I prefer the classical line and a very positional approach. However, there are tactical opportunities against Black's Queen-side if Black makes the wrong move. White always has the initive. 

I use it exclusively in bullet chess. I find it to be a fantastic bullet opening with flexible structure for white, always with a little initiative and never worse. Also very easy to familiarize, as most positions are similar. It is also uncommon so plenty of people don't have a clear idea of responding to it. However, I have not explored its practical strength myself in classical chess. 

agaisnt an unprepared opponent devasting.

Agaisnt a well researched opponent. Somewhat on the milquetoast side, but its quite flexible and even does not always mean  drawing.

the game that got me the NM title was the final round of the Amateur team south where i played a fellow NM known for solid play. despite the fact one of his sparring partners played b3 himself, i stuck to my guns and played 1.b3. the game seemed boring and passive and then next thing you know i swapped my fianchettoed bishop for f6 knight to inflict doubled  isolated pawns and won the endgame with ease. I dont think i spent 30 minutes in that game. That win made my team win. my teammates just evened the score in the other tables.

If you a creative player who likes to win, 1.b3 is a great opening. If you want to get some guaranteed theoretical advantage right out of the gate 1.b3 is not for you. 

If as black you play a reverse London, you equalizes immediately; in fact, if you play top moves recommended by Stockfish, you end up with an exact mirror of the London. The best thing about this defense is that it's super easy to remember.

That's not to say that it's bad for white, it's just that if white isn't surprised, you don't get any real advantage.

So the answer is, it's fine. It gives practical chances and could surprise an unprepared opponent.

I used to hate the london set up because if white plays clean, (e3, nf3, c4 etc), he has a hard time forming juicy counterplay. Until i realized white has a bunch of creative ways to pressure such a generic response. My favorite has been to play play e3-nf3-d3- Qe2!? with intentions of e4 and 0-0-0 ,, usually white will play either g3 or h3-g4 as well.

Vladimir Bagirov did, with success.

Its decent

@darkunorthodox88 - I'm usually very much against generic openings, but I only face b3 maybe once every couple hundred games or so and I'm not going to bother learning any theory when I can get out of the opening with a solid position with literally no effort. A couple of years ago I learned a 2...Bg4 line that's super annoying for white, but then the next time I played it like six months later I completely forgot the lines after move 2 and had a rough game. If the opening were more commonly played, I'd put in more effort.

Like any other decently sound opening, the nimzo larsen attack is only good if the person knows how to play it.

So did fischer. I believe he went 4-0. Although to be fair, 4 games is a very small sample size. 

here is a game from lichess i played today in 15 10

lots of wins i have with b3 (otb and online) have this kind of appearance . The position looks fairly passive and tame for black to worry much and then Boom breakthrough. Granted in this example, black simply did a mistake, but it shows this pent up energy many lines have.

I thought white was Aron Nimzowitsch lmao 

LOL you too kind. Nimzo and Larsen are among my favorite players though. I think it shows

chess praxis > my system

not quite 1.b3 but in the same spirit. 

Amsterdam Interzonal (1964), Larsen-Spassky 1964. a hypermodern art piece. that pawn avalanche must have been so satisfying to land.

https://www.chessgames.com/perl/chessgame?gid=1128624