Had my Deisre for a week now, also on Vodafone.
I don't think the signal is as strong on it was my previous Blackberry Curve 8900.
I think its been documented or discussed on here somewhere that the phones signal is slightly weaker than others.
Looking at my handset now I have 2 bars at H in my front room which is quite good for my house but on occasions this will drop down as far as G. In fact its now showing 3 bars at G !
My house is however a problem area for signal strength, I don't mind too much though coz I have enough signal to make/receive calls and I can obviously use WiFi to browse.