I've never really needed a tuner. I really and honestly don't use tuners often and I've never had any complaints (only compliments) about being out of tune. Tuning by ear perfectly isn't that difficult to do; rest chin on instrument, match an open note, remove swelling...tuned. Perfect 440 or whatever tuning the song's in I got the open note from.
This tuner is extremely easy to use. Clip it on the headstock or on the key cover of a piano, hold the power button to turn it on, tap the power button to select instruments and/or modes (chromatic, has instruments, C, flat, B, or F) which is great. Hold power button to turn it back off.
One thing it doesn't do positioning wise is swivel rotate. Can't turn it so the letters are upright with an instrument like a guitar on your lap in position to play it or strapped to you standing with it clipped to the headstock. Not an issue for me. It can be clipped to a volume knob or selector switch on electrics or the sound hole in classical wood instruments (like a cello, violin, acoustic guitar). It's a bit in the way to do that on an acoustic guitar. Not so bad on others.
It only folds up and down adjacent with the clip and spins 360°. The top of the digital display doesn't lean, fold, or swivel right or left. It doesn't do that at all. The display is big and bright enough this shouldn't be an issue for most people that have decent vision. My vision isn't great. I didn't have any issues reading it even with a medium upright bass standing with a strap on.
I tested this Donner DT-2 tuner on 20 different guitars including a uke, a steel guitar, a 12 string, a banjo, an acoustic and an electric bass, and a mandolin. I also tested it on a cello, an acoustic upright bass, an electric upright bass, a violin, a baby grand piano, and a drum kit after it arrived. Drum techs do use a tuner. Drums are and should be tuned to notes that match the key the band they're played with uses or they sound weird (because they're not in tune with the band). It didn't work well for the drum kit. I wasn't expecting it to. It worked but not great for that. It seems to get sound from vibration instead of a mic.
It worked on everything I tried it on that I could clamp it to and it worked pretty well except for percussion instruments. I compared it's accuracy with a pocket tuner, 2 different rack mount tuners, and 2 different (a boss and a zoom) tuner modes on FX processors I have. To be honest accuracy wasn't perfect but it's probably good enough for the girls we go out with.
To apply nerd info about it's accuracy the DT-2 was off 20° flat on everything I compared it's accuracy with. That's off, yes, but it's not horrible. That amount is only very slight swelling to extremely sensitive and trained ears on a person that knows the tricks on how to tune perfectly by ear. That ability isn't required to be awesome at playing stringed instruments. I don't know many people besides myself that use that technique to tune stringed instruments other than people that saw me doing it and asked me to share how to do it, amazed at how well it works. I figured out how to do it from music theory books making me curious about how sound works.
Overall this is a good tuner with some cool features not all tuners have. It's extremely easy to use and it's accurate enough it made even my wicked sensitive ears (I gained and trained and honed over 40 years playing music on every instrument I could get my hands or lips on) like mine. As picky as I can be with being perfectly in tune and intonation this tuner has satisfying perfirmance.
The thing I don't know, yet, is how long it and it's accuracy will last. I assume if it was treated nicely protecting it in the plastic packaging it comes in that opens and closes securely and keeping it in a hardshell case accessory compartment it has a good chance of lasting a very long time. I personally have doubts it will work forever and last a very long time if it's kept on a headstock permanently and/or never turned off.
Great tuner for a great price no matter your skill level or abilities. The clip-on festure is really handy!