I'm not an expert with phone developing, roms, or any of that stuff, but this I know:
When I bought my precedent (updating from a non-android straight talk phone) the people at the store warned me that this would happen. I wanted an android phone so bad that I ignored what they said. I think regular Straight Talk phones are on the Verizon network, I know the signal was awesome with my last phone, and the android Straight Talk phones are on Sprint. There's a map of coverage on StraighTalk.com showing android vs. non-android. I know mine is on sprint, in alabama, and thats what the store clerk warned me about. She said that "8 of 10 people return this phone because its on the Sprint network and it doesn't get a good signal". Well, she was right for the most part. My new android phone is on the Sprint network, and it doesn't get a good signal. Mine isn't bad enough that I want to return it though. After I rooted & flashed my ROM, customized the system theme and added a new launcher (GO Launcher EX), this phone ended up being pretty cool. I got a class 10 sd-card and use the sd-ext partition option on my ROM so I could boost my storage to almost whatever I want. As far as the signal goes, yes its the phone, but there are things you can do to help it I think. I recently did a 3g boost mod I found on these forums. I think it helped a little, there are things like changing PRL's (i've never tryed that). All I know is at my house I have 1, maybe 2 bars, and thats enough to talk. If I need updates or apps, I always have my wifi. In birmingham I have full 3g signal, and I'm covered on the main road in my town, I just save the heavy data usage for when I'm at home. It does suck to be out in the middle of nowhere with no signal though.