Pros
I worked in the Wellington office. Definitely recommend Xero to others as it's a very healthy company with an excellent working environment for engineers in NZ. Xero operates at scale and has a bunch of interesting engineering problems as a result, and while it depends on the pod you're being hired in to (sometimes you may have an option of more than one team if your PX rep/hiring manager thinks you may be a better fit elsewhere), you'll never be bored and will have a chance to work with some smart cookies using cutting-edge tech. I can vouch that at least on one pod you will be given the time to engineer solutions correctly without rushing them out the door. Excellent opportunities for career growth and promotion, if you are hungry for success this is the place to be. Xero culture is great, most folks are friendly and approachable and opportunities to have flexible working arrangements (remote working, later starts depending on your pod) add to the quality of life. Misc perks are beyond what most NZ firms will offer including unlimited barista coffee & fizz, free fruit, pinball/games machines, things like paddle boards & bikes to use at lunch, and frequent discounts from other NZ companies like gym memberships, insurance etc. The new Wellington office is on balance a great environment to work in.
Cons
Xero currently retains its startup hunger & speed due to its roots, but this will have to be maintained and as the company continues to grow it is taking on more of an enterprise nature as is expected. As it has grown so fast there are spots of tech debt that are proving tricky to revise, and some projects are hurried to meet deadlines that may impact you, as well as resulting in classic large company comms issues. This varies by pod and TL though and my experience had few issues with regards to this.