Actually the i3 as a chip terrible. If you can afford it get an i5 at least. i3 computers are really slow.
you can't compare a desktop i3 vs i5, desktop i3 is just dual core but desktop i5 is quad core. so i3 is pretty bad for desktop when compared with i5. but desktop i3 is still more powerful when compared to a Celeron.
but in sp3 it uses ulv mobile cpu, ulv mobile i3 n i5 are both dual core with the same cache size, same gpu(just lower max clock for i3). main diff is clock speed, but with higher clock speed, so goes higher heat output.
the issue is the sp3 new thin case n single fan cooler, it has problem exhausting heat out fast enough for the i5, so it handles it by throttling the speed of cpu n gpu down, so it brings the performances of the i5 down to a i3 speed. the i3 model from many reviews don't hv this heat issue. so it runs at its full speed.
i3 is a 11.5Watt y series ulv cpu and the i5 is a 15Watt U series ulv cpu. in terms of cost, Intel sells both the i3 and the i5 at the same price, at US$281. so Microsoft don't save any cost for using the i3 vs i5.
I also hv a desktop bay trail dual core n2820, I use it for my living room surfing, hd youtubes, hd video playing with vlc all no issues. so to say i3 is a terrible/slow chip is relative.
Everyone hv different needs and different chip cater to different needs.