Without knowing what the payment is meant to be compensating you for, it's impossible to comment.
Around two and a half grand for a broken finger nail is fantastic. Around two and a half grand for a broken neck is pathetic.
You should be guided by your solicitor but, if you're paying his fees, you should also ask yourself whether fighting for a small amount of extra money is actually worth it. (It won't help much if your solicitor gets you an extra hundred quid, but charges you two hundred for doing so!).
You also need to consider how urgently you nee the money. If the roof of your house is leaking (and you've got no other funds) it would be better to get the money to pay for the repairs now, rather than getting slightly more money later (when the leak has caused lots of damage and given you a far bigger bill).
Ask your solicitor how much longer you'll have to wait for the money if he challenges the offer. Also ask him if his fees will increase. And, of course, ask him what he thinks the chances are of the other side agreeing to his higher figure. Then make your decision, based upon what's most important to you.
Chris