Pros
Training - if you're in a technical role you will get the training you require from in house to formal/vendor training. Some of the benefits - access to company car/car allowance depending on your department or role. Successful company - Excell grew exponentially during my employment which is only a good thing on a business front.
Cons
At the time there was no pension offer (this may have changed) despite it being a legal requirement. Salary - in some cases it can be grossly under the market rate unless you're in the 'right crowd'. 'Clique-y' environment - some of the longest serving members stick together no matter what. Sadly this involves the HR department, so if you ever had a grievance your could forget about bringing up as it would most likely be swept under the carpet or quashed by a director. In other words if your face doesn't fit, you'll have a hard time convincing anybody of your worth. Most 'good ideas' to reward employees for their efforts either fizzled out quickly or went to the same people time and time again - see 'clique-y'.