I can't think of anything bad about leather seats- except that due to their expense your car may be targeted for theft.

Leather seats can be 'less welcoming' in winter than cloth seats. So, many of them are also heated- and heated seats in the winter are a joy.

I'm looking to upgrade the seats in my del Sol, but the 'standard' is to install leather S2000 seats. Unfortunately, none of them are heated. Even in California it gets cold enough to desire a warm bum- especially driving at night with the targa open.

I say go for it.