TriNet - Overall a good product, although lacking in some areas.

Dark mode is buggy. From an admin perspective, usability is great. Employees and end-users have far more complaints. Time off (sick time) is currently negative for everyone on our payrolls and has been for about a month. The dashboard can be unintuitive, like clicking Time Off and then having to click another link before you see time off data.

I contacted support for help with a benefits question (I always contact support as a last-ditch effort after checking every document and link I can find). I checked FAQs before contacting them, and they were unable to give a helpful answer. Instead they directed me to an outside vendor of which they gave me the wrong contact information.
We had an issue logged with them for 5 months regarding sick time after plans changed which caused all staff to have negative sick time. We manually tracked this for 5 months, they finally fixed it (hopefully).

Trinet is very well suited to handle a variety of time-consuming HR tasks, making them easier and faster. The Money section works well. The time off section has bugs. Notifications could use some work as there is no way to mark notices as read in the interface and the notification doesn't go away.

We had a large issue with tracking time off that doesn't sit well with our employees. Along with lack of help and lack of urgency from TriNet to get the issues solved.

We are a small company, do we use it across departments and sites? Yes, we are all remote working, so there are as many sites as there are people. We also have our entire staff using TriNet, so every department from Accounting, Admin, HR, Development, QA, and Management are all using this. Can't say for sure how great the scalability is as we are only about 30 employees.

We had an issue with application errors - took TriNet 5 months to fix it, mean while we had someone manually tracking and keeping up with many requests and questions about the application error which affected time off.
When we were all registering for Benefits during open enrollment there were lots of bugs that caused issues with registering for benefits or being able to see what benefits were available.

For the most part pages load quickly. Working for a software company we understand performance is everything, even a few seconds delay can feel like a lifetime, that being said, we ran into a few times where pages didn't load, information didn't load correctly, and an influx in users (like open enrollment) cause things to slow down.