Downloaded this on my Japanese Wii today and I'm enjoying it so far having played the first three levels. The graphical style is a little more cartoony than Contra III for Super NES, with more lively animation and greater use of sprite rotation, but it still comes out looking pretty similar overall. It is more smooth considering the size and number of sprites being pushed around here (and a few neat extra touches like glowing effects), but really that's no more than we should expect from this sort of thing. The music will be instantly familiar to Contra fans, though the instrumentation sounds more reminiscent of Treasure's Genesis games than Contra III.
The trademark Contra crazy setpieces are in evidence so far, the first boss being a fight against a humongous space caterpillar which has you hopping from bits of debris (from a space station that just exploded) as you re-enter the Earth's atmosphere. Oh and if you like fighting robot ninjas that hang upside down from giant missiles, this one's for you!