Plus points
1 Better search
2 Multi category
3 Better Comments system
4 Simplicity
5 Themes
6 Plugins
7 Easy control
8 Excellent SEO
9 Powerful Engine(uploading)
10 Social networking friendly
11 Security
12 Multi User capable
13 Free Upgrades
Why wordpress create problems?
1 Normal Server will create problem. If not WP tuned server it will be slow.
2 500 Internal Server error due to conflicting plugin or theme or due to problems in wordpress installation. PHP memmory limit also a problem.
3 Error establishing a database connection
If your database crosses the alloted quota, this error will come.
4 connection timed out: If your website do some thing more than you server can do or beyond server capacity.
5 Error 145, and error 28( rare case).