I spent some time over the weekend checking out Prototype and I actually prefer it over Infamous, even though it's quite similar and has it own flaws. The actual feel and style of the game is much more hectic than Infamous, the city you are in feels much more alive and full. The controls at times feel a bit loose, they aren't as tight as I'd like, however the gameplay is fairly fluid for the most part. Traveling around the city is quick and easy, and unlike Infamous you don't spend ages climbing up a building, you can just sprint up them.
Prototype has the usual story missions and side missions, though side mission have little use besides something else to do plus gaining some experience points used to buy and upgrade abilities. I think it's that Prototype seems like a faster paced game, plus the selection of abilities is a bit more varied as opposed to Infamous where everything is just electricity. Taking out enemies feels more satisfying also, most go down without much fuss.
I'll play a bit further into it, no doubt I'll find something that really takes the shine off things, I hear there are some parts that are ridiculously hard.
Also my copy of BlazBlue turned up today, it's something I've been waiting a long time for so I'll be sure to put up some impressions of it as soon as I can.