I'm new to Sharepoint, so here I'll start a list of Sharepoint Annoyances :)
#1: It lets you think you are designing relational data... but you are not!
Some examples:
I have a list of clients, and I have a list of contacts (or individuals) at that client's site. I am designing a form for entering job details and I want to link in to a job both the client who requested it and the contact at that site.
I want the user to pick a client and then a contact that is valid for that site, but I can't seem to filter them!
Secondly, there is no validation!
I want to have a form where the user can enter a start date and a finish date. No problems so far but logic dictates that the finish date cannot be before the start date! I don't have a way of enforcing that.
I'm sure there are ways around these, but right now they are annoying!