At some point, I think in the run-up to my G5 or perhaps the first adult learners' do I went to, I discovered that my iPod (nano, 5th gen) had 'Voice Memos' function. That is, it recorded, and you could play it back either through the iPod (built in speaker or headphones), or plug it in to your computer and sync it with iTunes and have it play back on the computer. This was OK for what I wanted.
At my next birthday/Xmas (can't remember which), my husband bought me a little Sony digital recording thingy (checked it: Sony MP3 IC Recorder). iPod sized, with stereo recording. Again attaches to coputer for playback, or has built in speakers. It can take headphones. It can also take an external microphone.
I haven't used it that much - mostly in exam preparation or forum event prepartion. However
, on Monday I used it in practising for the first time! I am learning a piece of music which I am very very familiar with. This has a good side - when I play a wrong note, I immediately hear it as wrong, because I know how it should sound. But, it has a bad side - when I play the right notes, I don't honestly know if the sound I am hearing is my playing or my knowledge of how the recordings I have sound.
So at the end of my practice session, I recorded a 'performance' of the piece. This has some benefits of itself for me - forces you to keep going and play the whole thing through, no stopping, no going back. This is a useful skill to learn if you are accustomed to stopping at mistakes, replaying the tricky bits, and rarely ever playing the whole piece through as you would to an audience.
But then I got to listen to myself, and the good news is the bits where I thought it sounded good, it does
sound good. And the bit in the middle where it feels like it all falls apart, is
where it all falls apart. Listening to myself back, I can pinpoint where it starts to fall apart, so I can focus my practice there for the next few sessions.
I don't think you necessarily need any fancy equipment to start with. It is likeyl you have something - computer, laptop, mobile phone, mp3 player, etc - with a recording functionality. Give it a try with what you have, not worrying too much about the quality for now. If you find recording useful, then you can look at 'upgrading' your equipment if you need to
As was said above, I think your playback quality is important - if it sounds rubbish on your mobile phone, that may be your phone rather than you
See if you can record something else (even if it is just holding it by the radio for 10 seconds) and you'll get a grasp of the recording/playback quality!