Like all mods, it comes down to whether you buy a good quality product.
I have to admit that I'm a fan of LED lights - that are done well.
I have a set on my R32GTR.
When taillights aren't on, they look stock.
When taillights light up, they modernise the look of the car. Sorry, it's a really bad pic, but should give you an idea of how they look during the day.