Elstree's my home base and I learnt to fly there, it has:
- a slightly interesting runway in terms of slope (all the better for practice)
- A very odd set of circuits (inner, middle, outer..)
- Can be extremely busy especially on a nice weekend with literally 100's of movements a day. Be prepared to master the go-around
-You'll learn to keep and eye on your wingtips when taxiing
- The FISO was still there the last I heard, you've just got to learn to deal with him.
-Close to Heathrow and Luton airspace, which will make sure you nail your nav
All in all, Elstree is a very good place to learn to fly given how busy it is and the extra layer of complexity due to noise abatement. You'll find most other fields very easy afterwards.