It's easy, it's short. The sprite doesn't turn to the mouse properly and probably rotates too slow. As I understand, the invisible walls are supposed to make the game harder. Unfortunately It just made the game worse. I do like when my game challenges me, but that wasn't a challenge at all. It was a time waster that made me look for a stupid passage in a safe zone. I wasn't really endangered by anything while looking for the passage. It was just a time waster. Also, you CAN see the passage when you look closely - it's a little bit darker than the rest of the stripe that's not passable. And that's actually worse, because it made me naturally look closer and use up my eyesight to detect a little gap.
The cars were passing in a pattern, everything was simple sprites, I didn't experience any sound effects, so I guess there isn't much to judge apart from what I have already mentioned. It's not a terrible frogger game, but it's not any good either. There's so many things I could think of that could improve this "just cross the street" mechanic. I see none of those in your game.