I live in Ely!
We love it here. We live near the train station and they have frequent lines into Cambridge, and it is oh... a 25 minute drive?
Another town to look at is Bury St. Edmunds. It has a train station as well but it isn't as big or good as Ely's, but still goes into Cambridge. Bury has more shops (Marks & Spencers, Body Shop, Next etc) - and is still cool. Rent is a LOT cheaper in Bury than in Ely.
We have a 2 bedroom house in Ely and it costs us 600 pounds a month. You can get 3 br flats for a decent price here, but they are all on the outskirts of town in new housing editions - which is fine if you have a car. I prefer living closer to town though because it is nearly impossible to park here and I have to walk everywhere. So if you are doing a lot of walking I don't recommend the new places.
As for Bury - it is bigger than Ely. Ely has more little shops, but with a proper high street and stores like WHsmith, Huge Tesco, Boots, Dorothy Perkins, Adams, Woolworths, WIlkinsons and Waitrose) and the cathedral is stunning.
ALSO - you can look at Newmarket. Again it is about the same distance from Cambridge, has bigger shops than Ely, has a huge horseracing industry, and is pretty cool - though I definitely prefer Bury or Ely.
I will SO MISS living in Ely, I completely and utterly adore this city. Cambridgeshire is a nice place to live. It is a really flat part of England and full of fields and farming and rural life, but then you've got little gems of cities like Ely and Bury and obviously Cambridge. And Cambridge ROCKS. I love it there. There are loads of Park & Rides as well (for commuting or shopping) so it isn't hard to access.
So! There you go. I'm more than happy to chat more about it if you've got questions. I've been here nearly 3 years (minus 6 months I spent in Essex) - and my husband grew up in the area.
** Bury St. Edmunds and Newmarket aren't in Cambridgeshire though, they are technically in Suffolk, but just as far (basically) from Cambridge as Ely is. Newmarket is actually half and half, and sits right on the border of the 2 counties.