A faster clock frequency will let your phone go faster, but it comes with some costs.
The power use of the CPU is (roughly) proportional to the square of the clock frequency, so increasing from 600 MHz to 1600 MHz will use 2.5 times as much power. On top of that, that power gets turned into heat, so it'll be producing heat 2.5 times as quickly as well. Your phone will automatically slow the processor down if it gets too hot, so it may be that turning up the max clock speed actually makes the CPU slower overall - because it has to keep "throttling back" to avoid overheating.
Changing the CPU frequency doesn't make anything else faster but the CPU. That is, if you're trying to play a graphics-intensive game, it might not get faster because it's limited by the GPU speed; or if you're doing things on the web, your internet connection won't get any faster.
In this particular case, you're asking about changing the frequency within the design limits. This ought to be safe, but some mods and custom ROMs let you genuinely over-clock the processor faster than it was designed to go, or to change how and when the power management reduces the clock frequency. Using techniques like this can cause serious overheating, enough to permanently damage the phone's hardware. Be very cautious if you should decide to experiment.