I'd rather have a stable game rolling out into more countries that's harder than an unstable one that I can enhance with 3rd-party tools. The server problems made the game unplayable for me.

The client's inability to handle the most minor of server disruptions without a hard crash made it unplayable for me.

Also its hard dependency on fetching everything from the servers (it looks like that even includes the pokemon 3D models - sometimes you clicked on a Pokemon, and had the catch screen with only the shadow of the Pokemon shown for some seconds until the 3D model loaded), and almost zero caching, even of static content like pokestop pictures.