heres the thing: You are not going to get many good, unbiased opinions from this forum. You need to seek these opinions elsewhere. The md/phd thread might be a good alternative.
Heres the bottom line: A phd is a doctoral degree. Treat it accordingly. It is paid, but it is still a huge commitment. It is a commitment you need to be sure you want to make. As people have indicated above, you absolutely need to get yourself involved in research. How else can you know you want to do research unless youve actually had your hands in it? No program worth attending will accept you without research experience (and a good understanding of that research experience). Talk to graduate students. Talk to post docs. Talk to your professors. Theyve all been where you are currently. You need to educate yourself. You need to know exactly what youre getting yourself into before you apply. This is a great first step.
There are good and bad points to going the phd route. First, the good points. For any program worth attending, you are paid a stipend (usually between $25-30k/year), tuition is waived, and you are given free health insurance. In the biomedical sciences, most teaching requirements are nil. This means your research is the focus. You arent necessarily being trained to be an expert in a specific area (though it happens as a result), you are being trained to think like a scientist. The bad parts of going the phd route is the lack of continuity in training and the uncertainty in graduation. Pick a good, well funded mentor and life is good. You go to several conferences per year, get publication opportunities, the ability to network, etc. Pick a bad mentor and life sucks. Youre stuck in a broom closet with minimal reagents and yelled/cursed at on the regular. Choose wisely. Some do, some dont. My undergraduate advisor gave me the wise advice to select a lab based on my relationship with my mentor/lab rather than my interest in the research project. Best. Advice. Ever. But, my point is that you can see how two people could have completely different experiences in graduate school in the same school in the same program.
And then there is the uncertain timeline to graduation. Unlike undergraduate or medical school, where you complete a specific number of credits and youre done
graduate school is a different beast. Your committee (4-7 faculty members) decides your fate. If they feel youve done enough work, you get the green light to start writing your dissertation and defend. If not
well, then that really sucks for you. I never had any problems with my committee. They were tough, but they never hindered my graduation. There are some real horror stories out there though.
Finally, to round out my wall of text and counter the above posts of resentment towards grad school, ill give you my story. I graduated with my phd in the biomedical sciences in 2009. Going to graduate school was the best decision i ever made. But, make no mistake, it is my life. I live and breathe research. I love it. And i have a strong record of achievement to show from it. Pm me if you have any specific questions.