Pricing comparison: The smallest GCE instance (2.75 compute units, 3.75 GB) should be compared to the medium sized EC2 instance (2 units, 3.75GB memory).
That's $0.145/hr GCE vs. $0.16/hr EC2 vs. $0.077/hr EC2 (heavy reserved 1 yr full time), so the pricing is competitive with Amazon - especially given the extra 0.75 compute units.
The only unknown is whether the compute units are equivalent - the docs only say they are Sandy Bridge-based Intel CPUs.