There are two elements to this I think; the light performance and the styling. The latter is perhaps a bigger reason IMO; the front end is literally transformed with the LED headlights and the triple chrome grill that comes with the lights.
It is a too pricey though for me, a shame really as the standard halogen headlights are a real penny pinching exercise and I can't think of another car that looks so different just because it has led vs halogen headlights.
For £1500 the SEL would be a no-brainer as the spec is so much better (includes the digital dash, nicer seats etc, 19" wheels etc)
Plus jumping from 1.4 TSI SE Nav to a 2.0 TDI SEL is a £3750 price jump for I can almost justify the addition of LED headlights on the SE Nav I'm not too concerned about the styling, it's more whether the light performance is worth upgrading for.
In the winter when it's dark most of the time...the quality of the light and the constant adjustments they're making automatically... makes them worth having...I love them..it depends on your own budget.
Ah I went for a tdi so it made sense. Well I have an old golf with halogens and currently an Audi with Leds. I live in the country with pitch black roads and the difference the leds make is quite a lot. Just find the halogens dull where as the leds light everything up clearly.