No, it is not good to restrain yourself...
When you and your partner are performing sexual intercourse, you just go out there and fully express yourself. After all, this is a women's who's sexually arroused you; take that erection and have some fun. If you hold back, your partner might think that you're not enjoying yourself, and will become more reserved herself in turn. Wearing a comdom during sex is, of course, medically advised, but if it interferes with your sexual enjoyment, don't hesitate to not wear it. After all, 64% of women interviewed preferred condom-less sex. Another topic, of course, if circumcision. If you're not alreay cut, it is highly advised to do so, as 96% of women interviewed perfer sex with cut males than uncut. And don't forget the sex toys! One last thing: Viagra. Use it. It's as simple as that. Even if you're confident in your erection, it can always fail you, so better safe that sorry, I say.