Works as advertised.
Writes like any fine gel pen but, because the ink goes clear when subject to heat, the friction on paper from the hard eraser on the top of the pen is enough to neatly erase any marks I make. Ink doesn't smudge or fade, although it possibly could in bright sunlight over time.
Pens can get a bit dry after a year or so (only one failed like this though out of several).
It is great to be able to replace without buying the whole pen again, even if they are not very expensive.
I use it for all my notebook activity now.