Earlier reports made some confusion between Nvidia's own Q2 and Q3 quarters (not all companies refer to the same months when they say Q2 or Q3, some are a quarter ahead or so) that led some people to believe that Tegra 4 will not arrive on the market until in summer, and Project Shield will not arrive until September.
At first glance, that would be very disappointing, but in the same time not entirely that surprising, considering how many times Nvidia has disappointed on this front. They've said both Tegra 2 and Tegra 3 were supposed to arrive in August or September 2010 and 2011 respectively, but they each arrived about half a year later than promised. Tegra 2 arrived for the first time around February 2011 in the Motorola Atrix and Xoom, and Tegra 3 arrived in late December 2011 in the Transformer Prime, but most devices didn't start using it until March and beyond.
But surprisingly, this may not be the case this time, and it seems that for once, Nvidia is going to keep its promise and launch Tegra 4 and Project Shield this spring. That doesn't necessarily mean it will be on the market early compared to the competition, but it should come out around the same time. The only question that remains is how competitive it will be.
CPU wise it should do well in performance with its quad core Cortex A15 1.8 Ghz cores, but it doesn't exactly use the big.Little set-up, so I'm a little worried about battery life. It uses a lower clocked Cortex A15 core as the companion core, but I think that if you're going to use this big.Little or similar strategy, then you might as well use something very efficient for those companion cores. And using Cortex A15, even an underclocked one, doesn't make that much sense to me. But we'll see how it does in the reviews.
The GPU performance should also be much better than Tegra 3 (my guess is at least 4x better), but that doesn't necessarily mean it will beat the competition. In fact, at least in benchmarks, it probably won't. Not to mention it's not very future proof as it doesn't support the OpenGL ES 3.0 graphics API, which means game developers that want to take advantage of those extra graphical features won't be able to do it with Tegra 4 devices, but only with the Mali T600+, Adreno 300+, PowerVR Series6 GPU's, and Vivante's latest GC800 GPU.
Right now I'm not very confident in how well Nvidia will do this year with Tegra 4 in the market, but it might still do relatively well in the mid-end of the market, much like Tegra 3 did last year.