The app:

* Constant nudging to buy more with all the usual high-pressure sales patterns (creating urgency, doubt, etc)

* Implies tiles with non-replaceable batteries will stop working after a fixed time (they won't).

Other things:

* The tile network is not as complete as I'd want it to be. I once lost my keys at work, and someone turned them in to security. It took a week before I was able to figure out what happened--I guess neither the finder nor anyone working near the security office had the tile app.

* Fairly high subscription fees for the tiles with replaceable batteries.

* Tiles are fairly thick. Even the new Tile Slim is pretty thick to put in a wallet.