I'd find out if "part-time with full time hours" means no benefits & factor that in. I have some classmates who were hired "part-time" only to work full time hours w/out medical insurance or a 401k. I personally favor full-time benefited positions over part-time ones. What are the job prospects long-term with the unit? Maybe see if you can speak with recently hired new grad RNs about their experience at the hospital?
I don't really know about this mandatory med/surg for a year myth that gets thrown around all the time. Fair compensation, high quality training, and future job security are all critical factors. If this is offered to you and happens to be in a specialty you're interested in, go for it. I started as a new grad on a specialty unit earlier this year - peds bone marrow transplant. I wanted oncology, I had a previous career in child education which looked good on my application and was offered a 5 month paid precepted training + two year full-time benefited contract at a great, supportive hospital. It was my first and only job offer, paying less than other hospitals, & I probably would've taken anything (since I was applying to every type of job under the sun). Just so happened I landed something I was looking for on the first go and I am very pleased with it so far. -- on a side note, night shifts are pretty aweful & I NEVER had any intention of working in peds but now I love it --
New Grads can flourish in any environment with the right support and training. Following what makes you feel inspired and excited in life is always a good idea. If ICU/Critical Care is where your heart is -- especially since you live rent free and can afford a little lower pay -- then I would say go for that one. I also see a lot of positives in the benefits, extra income to pay down loans +a broader nursing practice foundation, from the med/surg offer. It's really nice that you have options! You must be a very competitive candidate.
Let us know how it goes! : )