So - goko has a bunch of things that Iso doesn't
1. Official Art
2. Music
3. Animations
4. Artificial Intelligence
5. Single Player (its still there - even for guests - you can choose 2,3, or 4 players - but not 5 or 6)
6. Cool 3d avatars
7. A casual leaderboard for people who want to constrain their cards
8. Rewards for playing with your google account. Iso gives you no such bonus.
9. Adventure mode
10. Far fewer people in lobby - so you don't have to worry about chat spam.
1: Nominal at best.
2: A downside, as I listed above.
3: A big downside, as I listed above.
4/5: (same thing) Okay, I guess I can give you this one.
6: Doesn't do anything for me.
7: Eh, maybe, sure. "two levels of leader boards". I don't care about leader boards at all, but I can see where one could.
8: A downside. Don't have a Google account; don't care to. Google is evil.
9: Alright, adventure mode. Guests can't try it so I can't comment on it. This might be able to be counted as a positive.
10: I never encountered chat spam in Iso at all. A larger lobby's better, so you might occasionally see any chat at all. Thus, a downside.