Pros
Lightspeed is the company you go to if you want to take your career to the next level. Managers and executives put a lot of effort into creating the best environment for employees; something they take a great deal of pride in. A lot of effort is put into transparency and helping everyone understand what their role is in the company and how it impacts the company on the whole. I've never heard someone not feel that their work mattered at any level and in any department. There's also amazing support from the management. Lightspeed has the best attitude towards its customers and team spirit of any company I've seen.
Cons
The cons are mostly a result of the pros. Because the environment is so stimulating, and you never have a boring day -- it can become difficult at times to maintain the work life balance found at other places. If you're a slacker, Lightspeed isn't the place where you'll enjoy yourself. On the other hand if you're a hard worker, you'll never have the feeling that you're doing all the work.