This thing is incredible. The delay effects are awesome, the response is fantastic, and the punch-in for the looper is seamless. I have struggled for years to use loopers because they never seem to stop and start at the right time, but this guy does it perfectly. One of the coolest features is that you can set a tempo, record a loop, and even if you aren't EXACTLY on when you punch-out, it knows where the measure is supposed to end and adjusts it for you. I didn't upgrade the memory and I still haven't filled up the card yet. I even record the same loop with different layers to occupy 2-6 slots per riff. The best feature is that while in playback mode, you can rotate through a bunch of different loops and it doesn't change until it finishes playing the current loop. For example, if you start playback on loop 10 and then start pushing "up" to go select loop 23, it finishes the rest of loop 10 and then seamlessly starts playing loop 23. You could literally play an entire song by recording all the sections and then selecting the next segment while the current one is playing. Again, the delay effects sound amazing and are REALLY versatile and programmable. Obviously having a Tap tempo button is crucial (it has one).
One feature that I would love for it to have is the ability to toggle on and off each layer of a loop once recorded. You can accomplish with a semi-hack by saving a loop to multiple banks and then recording over each one with different parts, but that's fairly intensive and you can't ever remove the base track. Regardless, this pedal is incredibly worth the money and has immensely effected my writing process and ability to get ideas down without a full blown Pro Tools session or having other band members present.
It's also great for just hearing a riff on repeat to try and write lyrics.
If you are a guitarist or singer/songwriter, definitely buy this immediately.