Yes, most of that is true, but many of those effects are extremely rare at the doses we commonly use, and some of that information is misleading. Just to put things in perspective, here are a list of side effects of naproxen (common brand name: Aleve), a non-steroidal anti-inflammatory drug that is available over the counter:

Gastrointestinal: The most frequent complaints reported related to the gastrointestinal tract. They were: constipation*, heartburn*, abdominal pain*, nausea*, dyspepsia, diarrhea, stomatitis.
Central Nervous System: Headache*, dizziness*, drowsiness*, lightheadedness, vertigo.
Dermatologic: Itching (pruritus)*, skin eruption*, ecchymoses*, sweating, purpura.
Special Senses: Tinnitus*, hearing disturbances, visual disturbances.
Cardiovascular: Edema*, dyspnea*, palpitations.
General: Thirst

* Incidence of reported reaction between 3% and 9%. Those reactions occurring in less than 3% of the patients are unmarked.

Incidence less than 1%

Probable Causal Relationship: The following adverse reactions were reported less frequently than 1% during controlled clinical trial and through voluntary reports since marketing. The probability of a causal relationship exists between the drug and these adverse reactions:

Gastrointestinal: Abnormal liver function tests, gastrointestinal bleeding and/or perforation, hematemesis, jaundice, melena, peptic ulceration with bleeding and/or perforation, vomiting.
Renal: Glomerular nephritis, hematuria, interstitial nephritis, nephrotic syndrome, renal disease, renal failure, renal papillary necrosis.
Hematologic: Eosinophilia, granulocytopenia, leukopenia, thrombocytopenia.
Central Nervous System: Depression, dream abnormalities, inability to concentrate, insomnia, malaise, myalgia and muscle weakness.
Dermatologic: Alopecia, photosensitive dermatitis, skin rashes.
Special Senses: Hearing impairment.
Cardiovascular: Congestive heart failure.
Respiratory: Eosinophilic pneumonitis.
General: Anaphylactoid reactions, menstrual disorders, pyrexia (chills and fever).

(And that doesn't count the more recent concern about increased risk of heart attack and stroke.)

Yes, there are adverse effects of methylphenidate. Among the parents of children I've treated, and the children themselves, most of them are very happy with the results of the medication, despite the occasional adverse effects. I know that isn't very comforting to the people who suffer significant adverse effects from medical treatment.

But there are adverse effects of non-treatment as well. My main goal in treating ADHD is to prevent school failure. Not everybody with untreated ADHD is as resourceful and motivated as Little Hawk. Many just do worse and worse in school, feel worse and worse about themselves, and wind up dropping out. That's a waste, and a shame.

In medicine, as in life, we constantly attempt to balance risks vs. benefits. We try to do more good than harm. Most of the time, in my opinion, we succeed.

Aloha,
Mark