The sensation isn't on sprint lol. The evo 3d is obviously way way faster since there is no one complaining about lag. The GS2 is fast, but so is the Evo 3d. All the GS2 has is benchmarks.
Also not all reviews complain about the screen...I'm not gonna carry around a iphone and complain to myself about how the screen quality isn't the same on the evo 3d. The screen is QHD and still beats a lot of other phone displays out there.
Samsung has horrible support so idk about the GS2, it's an option but it all depends. The sensation is not that much smaller than the Evo 3d so it's not like that matters. I'm not chasing after the smallest thngs I can get....you can go have fun with you macbook air and worlds thinnest phone if you want but imo bigger is better

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The evo 3d has all the sensation has plus more so i'm sure htc is working on the camera now. Also the camera can most likely be fixed with an ota update, something that Htc actually does frequently....so really I don't see how the Sensation is better and who knows what kind of bugs will be on the sprint GS2. With their support we could end up with a broken gps, no wifi, horrible call quality and still have to wait 6 months to get it all fixed

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But honestly I'm just going to end up testing the GS2 myself when it launches, hopefully the 24th of July, with my Evo 3d in hand and if it can keep up i'll think about it. The only thing I can say bad about it is samsung's support. If the sprint version is as good as the original I might think about switching.