I like the Betamid as a shelter for conditions where I don't expect continuous rain. If you seal the seams it's plenty waterproof, and a decent pitch will keep the splashes at bay. We tend to use ours for early-season trips, so insects have not been an issue. Condensation can be an issue if the 'mid is pitched close to the ground, as you might do if the weather is cold and/or blustery. The alternative is a fair amount of breeze leaking under the bottom if it's pitched higher. I"ve learned to take a warmer bag or a silnylon bag cover if we're using the Betamid. The shelter itself is surprisingly wind-shedding, even without adding extra guylines, if you face one end into the wind. For added peace of mind, attach a guyline to the loop at the top of the upwind pole, and set an extra guypoint upwind. Rock solid.
I should note that ours is not a stock Betamid. My wife has sewed 3 useful modifications to the shelter: a 10" skirt of bug netting around the perimeter, a pull-out loop at the bottom of the back panel, and a tunnel vent in the peak opposite the door. The netting will probably help with insects, though we've seen few on our trips so far. The extra guy point helps to stabilize the rear panel if it's facing into the wind. And the tunnel vent is supposed to help with condensation. It may have worked - we had no condensation last trip - but we also had rather breezy nights so it's hard to know. On a $99 shelter you don't feel bad about experimenting in ways you might decline on an expensive tent.
As for the negatives listed by others, I wouldn't argue with any of them. I will point out that this is a shelter, a shaped tarp really. Comparing it to a tent that costs a lot more and is likely heavier as well isn't entirely fair. Also, I have run into both condensation and wind issues with tents as well. Air movement is key to condensation avoidance; without that both tents and shelters are going to condense. And many of the light, mesh-bodied tents aren't any better at keeping the wind out; wind comes in under the fly and through the mesh. Actually you can get clever and pitch the Betamid with the back into the wind and close to the ground, but extend the down-wind pole a little higher to get the downwind part up off the ground a little. As for slow to dry, no different from a wet rainfly. Hosing the outside with a DWR (we use the Nikwax stuff, but I've heard good things about Revivex too) will minimize the wetting. Finally, comparing the weight to Silnylon shelters like the Nighthaven isn't a fair comparison. Spend the extra $80 on a Beta Light and then make the weight comparison.
Not that I don't find the Betamid annoying at times. It's basically an A-frame, with a peak-and-valley skyline to boot, so headroom is a bit hard to come by if you're used to arch-pole shelters. The supporting poles are inside the tent with you, so maneuvering is a bit of a pain. But these are inherent in the form. We've found the Betamid to be a versatile shelter, better than I expected actually. Small in the pack, reasonably light, and uses poles you might well be carrying anyway (your trekking poles). Weight, even with the bathtub floor, is competitive with tents of the same space. Seems to handle the weather just fine. You can go lighter, but for this price you'll be hard put to find a better shelter.