Budgeting

In this price range you can take your pick of the competition - AMD has three different options for around the £100 mark and that should give pause for thought for even the most ardent Intel fan.
First off there's last month's new AMD offering, the Trinity A10-5800K, which is the alternative for anyone who's looking for integrated graphics performance. The HD 7660D graphics in the Trinity chip outperforms the HD 4000 on the Intel side by a huge margin - we hit 27fps in Batman: Arkham City at 'v high' settings at 1080p. The i3-3225 barely managed 16fps.
In terms of CPU performance the i3 has the edge, but with a little overclocking of the AMD chip you can close the gap.

Benchmarks

The i3-3225's general CPU performance is pretty good, but when you consider the similarly priced AMD chips - with access to overclocking - it starts to look a little off the pace. It will still keep a decent GPU filled in games though.
CPU rendering performance
Cinebench R11.5: Index score: Higher is better

INTEL CORE I3-3225: 3.25
AMD FX-6200: 4.32
AMD A10-5800K: 3.05
CPU encoding performance
X264 v4.0: FPS: Higher is better

INTEL CORE I3-3225: 18.82
AMD FX-6200: 27.81
AMD A10-5800K: 18.83
CPU gaming performance
Batman: AC: FPS: Higher is better

INTEL CORE I3-3225: 126
AMD FX-6200: 110
AMD A10-5800K: 74
For us, the real competition for this i3 chip is the six-core FX-6200. For the exact same price as the i3-3225 you get another two cores for your cash and that makes for much higher multi-threaded performance. Again, the AMD chip can be overclocked where the Intel can't, putting the 6200 almost on the same CPU level as an i5 at stock speeds.
So, the question I posited earlier regarding our recommendations at the budget level is actually an easy one to answer. There are really two options here, but neither of them is Intel-based.
If you're not going to let a discrete card anywhere near your PC then the Trinity chip will deliver almost gaming-capable performance on its own, and the FX-6200 will defeat the i3-3225 in most tests. It's close at stock speeds, but the Intel chip falls behind when you start to consider the impressive overclocking performance of the AMD chips.