I've had two thoughts about what might make it more interesting:
1. Make it so that you must know/recognize the spell you're trying to counterspell. That is, make a recognition Int check using Arcana skill (or possibly Religion?), to see if you know what the spell is and how to counter it. If you don't know what the other caster is doing, you don't know what to do to counter it. Obviously, your DM would have to allow this use of the Int check combined with the actual Counterspell, since they both apparently technically count as a reaction.
2. Make every counterspell use an ability check roll. Possibly a DC 10 + spell slot level being countered - your spell slot level?