Check out some reviews online - it is $90 some places, but you can also find from other users the pros and cons. Especially as you say you have access to a gym and you only really want an alternative until the weather warms up because of the baby, the cons of it being a very loud piece of equipment that you have to hold on to the handles...I would skip it. If you must stay in, getting a couple workout DVDs, or even just finding some stuff on youtube, is probably a better (and cheaper!) idea.
As far as manual treadmills in general, my gym has a high-end/commercial one and it's a great piece of equipment - since you're legs are actually powering you and the machine and it has a natural incline, it really is a workout. I can do 30 minutes on a regular powered treadmill but am usually winded after 10 on the manual! However, that's a $6k piece of equipment, vs a $100 one.
Do something everyday that your future self will thank you for.
| current weight: 179.8