My iPhone 4 is fantastic! For me, the best thing is the retina display. With the book reading apps, especially the Kindle app, the letters look close to e-ink (not outdoors of course). Luckily, I don't have any problems. Just to be honest, if I cover the antenna, I can experience the lesser bars. However, I always use a case (my Sena wallet case from my 3GS still works with my iphone 4 with a little padding). Thus, it doesn't happen.
Hopefully, for the many who do have problems, there will be a fix or fixes, soon.