I've been on Toprol XL for about 2 years and have ADHD. I can't take anything for the ADHD- certainly not stimulants, (Adderall was great for the few months I took it,) and Strattera didn't do anything but have side-effects.
I don't think I'm any different because of Toprol, at least regarding my ADHD.
I've been on a beta blocker called Atenolol for years, and started Daytrana in Feb. 07. No noticeable problems; I do think beta-blockers have a calming effect - in fact, I've known docs who prescribe Atenolol temporarily for people withdrawing from drugs who have panic attacks.