There are a few problems with the Symbian environment... some of which are the reasons for me deciding to try something new...
- Closed development - Only Nokia and a few selected partners have access to the core of the operating system, and ONLY nokia is able to release OS changes and upgrades. So if there's a bug, you have to wait till Nokia fixes the problem, which as was the case with my N95, Nokia will ignore you for 6 months while working on the update...
- Limited access - only certain parts of the operating system can be access or changed. So true flexibility is not permitted, you can only access certain parts of the OS's inner workings and only change some things. While it's more than enough for the average user, power users would like more access.
- Proprietary access - If you want to sync the phone to your pc, you're going to need to use Nokia / provider software. So you're once again limited to the features and abilities they choose to give you.