I have an ispindel.I like that I have a guide as to how the ferment is going and also a temperature reading.The exact sg reading is not that accurate on mine but I get my og from a conventional hydrometer and I dont feel the need for an exact fg.Mine came ready calibrated , it is possible to calibrate them yourself and possibly improve accuracy.As mentionned already the wifi range is poor especially inside a corny which I use for fermenting.I sit my keg right next to a wifi extender which makes it ok.I typically lose readings for 24hrs at peak krausen and I think that happens commonly.There is a separate relay you can buy to boost the signal which is probably the best solution,it costs just a bit more than a range extender.Overall its a useful toy,its fun logging in and seeing whats going on in there updated every 15min,you just need to know its limitations.