The main problem is its speed. It lags terribly, from startup and all the way to when it is fully functioning. Popups, menus and the like are all delayed from when you actually select them.
The phone saves texts, and has a cap of 500. It is frustrating to have to delete a bucketload of messages (on top of the terrible, terrible lag) every few days or so.
Internet is slow, everything is slow. Every action this phone performs, including calling, is slow. It should be called the INQ Slow 3G. There is nothing good about it.
The 'OS' is horrible and whoever made this phone should be fired and buried. I won't give it a 0 because it functions to a certain degree, but it really is terrible. A Samsung or an iPhone is expensive, granted. But they are infinitely more reliable.
I will be stuck with this phone for a while, though. Just remember that it's absolute garbage. Buy at your own risk.