Has anyone been there, any tips for board/lodging/sightseeing etc.?

Not much to see - Pleanty of cheap hotels no need to look or make a reservation. Good place to stop for a while if going to Mengzi or JianShui.

I remember the smell of a large industrial plant of some sort. However, the place had importance as a major stop on the French RR completed in 1910. I looked around RR yards and housing near the RR for something of interest but didn't really find it. This was about 2005 or 6.

air is of pretty bad quality due to large industrial plants as Alien mentioned. However, the vibe in the town is very pleasant and there's a nice park to amble around in. Good for a night and half a day.

South-east Asia's largest mosque (allegedly) is in nearby Shadian and worth a visit if only because it's so odd in the middle of nowhere. Easy access to Mengzi, Jianshui and Gejiu from there and of course a main stop on the old railroad. Trains between Hekou and Kaiyuan run twice a day, trains between Kaiyuan and Kunming up to 6 I believe (mostly industrial freight). I stayed a night (www.crazyguyonabike.com/[...]

Click next for the next morning and pictures of the mosque.

Well, i visited the palce the last few days. 3 and a half hours by bus from Kunming. Beautifull scenery all the way.

I found it to be a lovely refreshing and peacefull town, it seems modern and well-to-do, with a seemingly friendly and well mannered population. But...not much going on. It was almost impossible to find a barbeque after 11 and everything was closed down by 00.30. Stayed at "home 家" hotel, an excellent hotel for 150kuai. Western food is non existant in the town but along the river there's an expensive, plush coffee place (30kuai a cappuccino). There are a few places selling (thai inspired?) food not usually found in Kunming or China. Contrary to whats noted in the comments above, i found the air great (though locals said its usually much worse).
Being 50% minorities I was kind of expecting to see more minority costumes and manners but I saw nothing at all. The dialect is understandable.
Agreeing with Bluppfisk, The place is good for a night and a half a days visit.

The park is very pretty at night when all the old buildings are lit up with brilliant lights.

I walked north of the city along the old French railroad, through an industrial area, then through a tunnel, and into a very hazy valley full of open pit mines. It wasn't the pleasant experience I'd expected so I have up after one day and hitchhiked back to the main highway with some police who were concerned for me and didn't think it was safe that I was there.

The history of mining in the area is interesting - tin mines going back a couple thousand years and more, significant for the rise of early Yunnan political entities and, of course, important for sparking French interests in Yunnan and the building of the RR from Haiphong, 1910. .