I've been using the Adonit Jot touch 4 and it's been perfect. I see Adonit actually just released a new model with different tip and am a little annoyed as I would have maybe gotten that one instead.
Edit: and I see the jot touch 4 is no longer on their website but is available $20 cheaper than I paid for it on amazon. Just saying.
- I think the tip has the potential to scratch the screen. But I don't want to use a screen cover on my ipad. We'll see what happens.
- gets a little jumpy sometimes and I have to go back and redraw a line that came out a little wonky.
- palm rejection is crap. I got this really cheesy glove that takes care of this. Looks lame but improves the experience 100%. http://www.thehandglider.com
- pressure sensitivity is great.
- if you have this it means you're probably using procreate which IMO is the best digital sketching tool ever created.
Overall, worth the cost? If you are a professional, hell yes. I would say it's even a necessity if you plan on doing any serious drawing/sketching. The musemee notier stylus that I bought as trial backup is fine and probably great if you're a casual user but is severely limited in the procreate app.
Not like sketching on a Cintiq. Better, if I may be so bold. Love having the retina display to work in and procreate is so fluid. And if mobility / portability is a must for you, you can't go wrong with the ipad/procreate/jot touch 4 combo.