Nora008, you do realize that W10 Mobile is yet far from a finished product, right?
If you install W10M now, that means you're interested in giving MS feedback. You'll find many apps that don't work, crash, or are slow or lag. If you're just looking for something new but need your device to be reliable, you shouldn't be installing W10M yet.
If you install it, don't come complaining about it not being completely reliable. It's not supposed to be.