As an app, it's fine. Some graphical errors now and then and the battle pass UI can be somewhat of a mess what with like 4 different forms of freemium currency, but that's probably expected now with free games like this.

The Pokemon TCG itself is just in a really crappy state at the time of writing this. It doesn't feel like there's a lot of flexibility with deckbuilding, but that's just my experience. Everyone that loves whacking off Charizard so much is a FRAUD and a FAKE FAN