Hi DDDriver, I flew into and out of TNR last year, and I don't remember it as being too traumatic. I mean, it is a small African airport, and meets your (or at least, my) expectations. Immigration is mildly chaotic, baggage reclaim reasonably efficient, there is a slow currency exchange office just outside the baggage hall where you can change major currencies into great wads of Ariary - you will need small denominations, and a little goes a very long way, so don't change too much. If the plague epidemic is still ongoing you will be given a little warning leaflet on the subject, which is a nice touch. Don't let that put you off by the way, chances of a westerner (ie someone with money) catching plague are extremely low, and it is eminently treatable. The airport toilets are moderately horrible -worse than Manch but better than Addis - use the one on the plane if you can. Traffic in Tana is horrendous, so be prepared for a long transfer even if your destination is only a few miles from the airport.
Speaking of Addis, have Ethiopian started their flights to MAN? I would certainly recommend them, though ADD is not a nice airport to transfer.
I hope you have a wonderful time, whether on holiday or business. Madagascar is a spectacular country, with friendly people and amazing wildlife. Very memorable, just not the airport, even for a flying buff like me.