Probably the materials that are used to make it to reduce the cost (although still looks very nice) and skimping on some other parts etc.
It is actually by ZTE and is known as the blade iirc, orange just rebranded it pretty much.
Apparently the speaker is pretty good and I would say that it wouldn't be any worse or better than most of the other mobiles today.
Texting is very easy, you just have a normal stock android QWERTY (if you root and flash) keyboard and when you turn your mobile into landscape mode the keyboard will also turn, so will be much quicker and easier to type.
And if you don't like the keyboard then you can download a number of other ones from the market or from XDA e.g. the HTC_IME which everyone seems to rave about.
Although is this is your first capacitive touch screen mobile, it might take a bit to get use to it.
BTW I don't actually have the san francisco but have been following the thread about it and looking at reviews when it came out, I have the samsung i5700, but it is pretty much the same when it comes to using the keyboard
The only thing, which people have complained about is the poor camera and video recording and that is really it tbh.