Pros
The company is expanding rapidly and generally has very friendly staff and customers. You get decent local discounts and learn plenty of new skills (depending on which department you work in). I thoroughly enjoyed a lot of my time at Ecotricity which was mainly due to co-workers and job satisfaction (for the earlier part of my career). If you are looking at Ecotricity for a career start then look no further, this really does look great on your CV and you'll learn many valuable skills, compared to other companies Ecotricity does to an extent treat their staff well.
Cons
I worked for the company for 3 years and went through many company changes. I've worked for large corporates before and couldn't help but notice some clear issues with the company. The first thing I noticed was some bullying within certain departments, mainly from above team leader level - this did tend to filter down as well. The second issue was inexperienced members of staff being fastracked to team leader level without the essential skills required to do the job - if the face fits count yourself as more likely to get a higher up role- this is great for the individual however the teams really did suffer as a result (lack of direction and a voice to upper management due to manager not wanting to cause a fuss). The HR department were not great either with complaints. Lastly, this being the main reason I left and from what I understand from current employees is getting worse is communication. When I worked for the company we had half yearly company updates with a clear structure of changes that were to take place, this changed to yearly and then got called off and never re-scheduled. You could be working in one building one week working alongside certain departments, the next week with hardly any notice you would be moving again, absolutely no communication. This really impacted on staff morale and created a "them and us" feeling towards management. If you are thinking about starting at ecotricity with the view to progress your career internally, I would definitely think again. There are no pay brackets (you will be paid the same as someone with less, even years less experience). You will then struggle to progress due to the amount of people hoping to do the same.