I dont want to go into too much detail because i havent the time, but:
His "success" so far has largely been since hes been able to ride a strong economy; that was created for him by the tories. Ken Clarke's excellent management as Chancellor paved the way for him to take the glory for it.
He has survived by borrowing excess amounts of cash, yet nothing has actually improved. Our trade deficit is only going to be getting larger, and i doubt wel see anything positive for it.
now, GDP figures show things are quite good; since so many extra imaginery jobs have been created by Labour. However production is what you need to be looking at, and the country has not become more productive because of it. This is obviously going to cause huge problems in the future. Production in the public sector has actually fallen 10% since Brown came in (possibly Parkinsons law playing into effect?)
Overall i dont think hes done well at all; taxes have gone up on average £2,000 a person (man woman or child) and nobody is seeing the benefits for it.
However, he has been very calculating in the sense that everything he has done has not been for the country; but for his own and his parties political gain. Many things he has done have been done for the figures (employing a million people to do nothing for example; more money going into public services, employement coming down, GDP figures stay up.....looks good statistically doesnt it?)
So, hes been very good politically; but not economically. The sooner we get rid of him the better to be honest
Also, anti-blairites might be interested to know, Gordon Brown is often talked of challenging blair on various issues. He is more socialist than blair ever will be.
The only challenges he puts forwards are ones where he says he wants to be PM, and Blair wont let him. Then they fall out and sulk about it for a while.