The only improvements I would suggest are that it could do with a few stereo effects return inputs - it has several switchable pre/post fader aux sends yet you have to use input channels to bring external effects back into the mixer. Also some insert points for inline effects would have been useful, as would a number of channel compressors.
It would also have benefitted from a monitor output section. You have to feed your monitors from the main outputs or group outputs with no switching between them and the only volume controls to the monitors are your main or group faders.
In practice it's perfectly usable and fun to use, the audio interface is the key to its appeal for me, but those few additions would have made it a far more user-friendly mixer, albeit at a higher price.
Nevertheless, I heartily recommend the Signature 22 MTK as a mixer and audio interface if you have a number of hardware instruments and effects that need plenty of inputs.
The lack of returns, no control room output, no inserts, these were a deal breaker for me.
I’d recommend getting a multi-channel interface, and pair that with a a more comprehensive mixer, there’s the Soundcraft FX16, or the Yamaha MG20XU, with comps and 8 stereo 8 mono inputs, the 22 MTK is almost perfect, great sound, but the compromises would make it really annoying for me, it’s meant to be used with a DAW at the heart of its operations, but if you’re heavily into hardware outboard, it’s not really a good idea IMO.
Thank you for the suggestion, although getting a more comprehensive mixer and putting into an audio interface, would be WAY to expensive, hell I could buy 2 maybe 3 soundcraft signature 22MTK's with that money. Not to mention that fact that it would take away from the ability to be able to EQ after the track has been recorded, with that, once it is in the computer, its in the computer.