"limitations and problems.." not sure where to go with that one. Are you coming from Palm OS? Once you get used to the PPC platform, and find the software that suits YOU, you will be calling Palm OS "limited, ancient, unstable..."
Read these forums with great detail, especially the "ppc software" forum. You will find TONS of software to check out. Off the top I strongly suggest:
Set up a push mail account. Mail2web has them free, or for 2.00 a month they will give you the option to reply to your emails with ANY email address you have. It also keeps track of your phonebook, calendar, tasks, and notes. All over the air (OTA), and super fast!
Weatherpanel and Phonealarm get a lot of attention. I personally don't care for phonealarm, but most others do. You will figure out your preferences along the way. Weatherpanel is great, but requires some effort, so I suggest getting to know the phone first. You will fall in love, and I can't wait to read all about it here