The benefits of switching account are varied - again, it depends on your reasons for switching.
If you have been dissatisfied by the customer service you have received at your previous bank, seeking an account from a reputable provider could raise the satisfaction level.
On a more material level, switching to an account which pays a higher rate of interest might raise the amount of money in your coffers.
And if it doesn't work out, you can always switch again - the Banking Code dictates that financial institutions should allow their customers to switch to a different account at any time, without penalty.
Many accounts will come with added features as standard - such as an overdraft, which might be interest-free in certain situations, typically when the accountholder is a student.
Finally, you could find that there are benefits to having all of your accounts with the same provider - such as being able to transfer money between your current account and savings account at cash machines, or being able to obtain a credit card linked to your main account.