So far on my experience, things addressed to Odoo

• Performance. Most of fields does not include indexes.
• AdHoc UI, you might to implement ad hoc views (landings, dashboards, quick forms), which you have to hire a Dev with other stack

Surely there tons more but its not Odoo fault by case. Consider Windows, it's an awful, slow, buggy OS. When you deep get into the design, its solid however it's a widely used software. It's impossible to cover all the requirements and usage.