Let's not forget this unit was used on stage by multiple international musicians on tour

I'd like to clear up a thing before going any further: this multi-effect unit has been used by so many professional musicians there's simply too much to mention. When it came out, it was probably the best multi-effect unit on the market, and while Boss GT-series, Digitech and Line 6 themselves had pretty innovative multi-effects unit before, the M13 (and M9 and M5) were all the rave for a couple of years.

Nowadays Line 6 has the HX Effects unit which replaced the M13 directly, and even if it has many new and improved excellent effects replicas, the HX Effects also has most of the M13 effects in their original programming.

I could talk in great extent about which effect is good and which is less, but let's just put it this way: delays are nothing short of awesome. the reverb are very very nice, the modulation effects are so various there's literally weeks of exploration to do, the overdrives and distortions got the heat in reviews but I find them mostly quite pleasing and even though I run standalone od, disto and fuzz pedals, there are some gems hidden in there too!

One of the best thing of the M13 was the introduction of a separation point between "front of the amp" and "fx loop time based" effects selection. So you can run all the od, disto, fuzz, modulation in front of the amp and delays and reverbs hit the fx loop, just as it's supposed to be. It works really well and it's one of those things that makes you go "it's so versatile, I can't get rid of it".

The looper is not very versatile, but it does offer more options than just record/overdub, like half speed and reverse. You can also set the looper to be pre or post fx.

2 expression pedal inputs is very nice to play a delay swell on one and a pitch-shift-whammy-type effect on another for immediate access.

I really, really love my M13. The only bad things I can say about it have already been fixed by third party suppliers and modders, like the somewhat poor quality bult of the switches, the lack of a master volume etc... Google it and you'll find it.

Bellsls & Whistles

The samples in this board are pretty good. I can't get the sound out of the tube screamer that I get from my Ibanez. I like the spring reverb - very Fender-like. It has a very deep reverb that I enjoy pairing with my Les Paul to get that classic Fleetwood Mac Echo often used by Danny Kirwin and Bob Welch, the kind you hear on Future Games and Show Me A Smile. There are a lot of samples to choose from for those who love many different effects.

Wonderful piece of kit

The M13 presents a breadth and depth of sounds and opportunities to combine them that is frankly mindblowing. It's been a trusty and reliable steed for many years. However, I currently use it in combination with a BOSS ME-50 and a Line 6 Spider Valve 212 (which I use to switch between clean, crunch and distorted settings with and FBV Shortboard), and to simplify switching and set-up times, I'm planning to retire all three of those, in favour of a GT-100. As per my review for that item though, the GT-100 seems incapable of replicating some of the filter and synth effects that I rely on in the M13, so it may have to stay in the rig until a software update is released for the GT-100.

A Versatile Tone Monster

This is one of the very few Line 6 products that I love. Possessing the capabilities of 100+ effects and a floorboard-like arrangement, it is incredibly easy to use for any guitarist at all familiar with pedals. Its best sounds are its reverbs and delays, as they accurately emulate the units they model. I'm not as familiar with the filters and mods to know how accurate they are, but they sound good to my ears. The one sort of letdown are the drives. They don't sound as organic as their real-world counterparts, as they lack warmth and complexity; however, they aren't terrible and I use them with confidence, even if they don't stand up to personal scrutiny.

Effects all in one

Instead of buying a dozen different pedals, I opted to get the Line6 Stompbox Modeler. It has good distortion, delay, reverb, among many other effects, and a couple different effect settings to boost your signal before it hits your amplifier. I added an expression pedal in order to mold the speed of my delay on the fly.

Replace Almost All Your Pedals

A more versatile board I cannot imagine. The amount of effects this thing emulates is staggering. And by emulating, I mean virtually exact copies. A/B'd several of the stomp models with the real thing and cannot tell the difference. This is the ultimate all in one pedal board. I don't know how much all these effects would cost individually but I know I don't have that kind of money.

Not as good as M9, great option for avoid other pedals

Used to have it, You can have 4 stompboxes at the same time with 3 different pedals per stompbox. The bad thing is too big and heavy. I prefer M9. Check my review of M9, the effects are the same.

Praticidade!

Excelente multiefeitos. Me fez deixar um pouco de lados os pedais individuais.

Irreplaceable

This is the workhorse of my rig. I use this for all of my mods and delays, as well as boost. The looper comes into play every now and then.

Great!

Great sounds, specially the modulations and delays. The distortions could sound better, but they're ok...