Liepzig has lots of potential but buying the correct property is key. I would start with older character but recently renovated property well located.
Some of us here including myself have bought blocks of flats, but beware it is not a walk in the park - the rules and regulations can be pretty onerous & complex. I have said in the past I will consider taking a 'free' equity share in return for joining someone else's venture should they think it appropriate. I have a good contact (dealt with him over 2 years) for repossessed blocks - but you need big bollogs to buy these. I bought one of these. Sure the yields can be fantastic (20% not at all uncommon) BUT, all you get is a piccie with a few details*. Almost no buyer visits the offers as there often is no time and no one WILLING to show you round. This suits me fine but I find most others want all the boxes ticked so auctions often are'nt for them.
*Having said this there is often a full German report with each block which has a lot of detail about tenants and an official valuation but there still remain many unaswered questions such as 'can I let the empty units', 'what is local demand like' 'how much to fix the place' - you just wont get answers to such questions. The German dealers have no time for English time vampires armed with Which magazines. Put yourself in thier position: would you want to deal with a) a German cash buyer who makes on the spot snap decsions AND SEES IT THROUGH TO COMPLETION or

some ******** English fella with long lists of dreary 'petty' questions that will probably not have the where with all to actually buy at auction?
So auctions can be opaque and a bit frustrating but worthwhile IMO - just avoid anything falling down or made of conrete which might need £200k of improvements.
Finance in Germany is very cumbersome for us foreigners. Even with the help of a good broker I find it a real hassle.
For blocks of flats you might get 70% but 60% is more likely if you are lucky! Better to buy cash and then refinance at leisure.