I've had DirecWay for a couple of months now, since moving to rural AZ.
As mentioned, there is a huge difference between up and down. There also appears to be a huge difference between night and day (well, between peak hours and off-peak hours).
I see speeds in these ranges:
off-peak:
1000-2000 Kbps down, 30-90Kbps up
peak:
150-500 Kbps down, 5-40 Kbps up
During peak hours the return channel can be much worse than dialup.
The biggest single thing I hate is the latency. Once you get a data stream moving, the speeds above apply, and this works well for http and ftp, but not for VPN or telnet or gaming.
On a LAN, latency is typically way less than 10ms. Go to a T1, and it can go from 10 up to 100ms depending on how far you are going. Dialup runs 150-250ms. The theoretical
minimum latency you can get over a satellite return system is in the neighborhood of 650ms (due to the distance the signal has to travel). More realistically, you will see off-peak latency around 800-1000ms, and during peak it can surpass 2 seconds.
Couple of good online forums to check out, for lots of good info and tweaks:
DSL Reports satellite forum
Copperhead