S.W.
I agree - talk to a financial planner about it. I'm not a financial planner, but here are the things I, personally, would look for before investing in my employer's retirement plan -
1. An account that I can manage easily (preferably online 24 hours a day) with a variety of investments that I can select - stocks, bonds, mutual funds, etc. - so that I can set my tolerance for risk and diversify to my satisfaction. If you're far from retirement, you can probably afford more risk than someone who is within 5 years of retirement, so it's nice to have that kind of control.
2. A plan where my employer matches my retirement deposits (my employer matches dollar-for-dollar of my deposits up to 5% of my salary - that's free money that I should not be turning down.