The signal definitely goes up and down on my Eris. I haven't dropped calls, but I do believe that the phone is wasting a LOT of battery, thinking that reception is bad some of the time.
The bars can go from full, to one bar, to 0 bars, to 3 bars, to full again, just sporatically all of the time.
This is actually an issue that, I feel, is the BIGGEST culprit in draining our batteries so fast.
I honestly think the HTC antenna is garbage, but that Verizon's signal is generally good enough that this is acceptable.
Set our phone down next to a Droid. Watch the bars on the droid. Watch the bars on the HTC. The droid's, holding still at 3 or 4 bars, while the Eris moves between 0 and 3 (sometimes 4) sporatically.... is an indication of something important.
I've suspected the HTC antenna from the beginning.
I think this thread, if it is a judgement of the phone's antenna by a jury of it's peers, is a GUILTY verdict.