I stayed here for 3 nights in October 2010 for a conference. I'd come straight from Bruges where I stayed in a much posher hotel, so maybe my expectations may have been set high, but found the Astoria to be, well, not so posh. Actually there's not much wrong with it, but it just doesn't shine. Mainly it's the room - a slightly odd shape (long and thin) due to its location at the end of a corridor, without much floor space to put a suitcase and - for me the worst bit - a thin cabin-style bed with only a single, thin duvet not much bigger than the proverbial postage stamp. Also no tea/coffee in the room, which I just sort of expect nowadays, unless you're in a real budget place (which I don't think this falls into). But there's a nice LCD TV in the room with BBC World and CNBC for English language, plus some clever internet facilities which I didn't use because I bought in-room wifi access (at 12 Euro for 24 hours - you can buy 2 hours for 10 Euro, but that's clearly not worth it, or I think it's cheaper for lobby access - but really there's not much space to sit down there!).
Staff were friendly and helpful though, particularly the chap who checked me in on the evening I arrived, who was happy to chat over my free beer at the bar (which I got as I'd booked via their website).
Location I'm not so sure about as I really didn't have much chance to explore Berlin while at the conference unfortunately - though I got the impression the tourist sights were a bus / underground ride away (e.g., Brandenburg Gate, East Berlin). There were good shopping centres around the hotel, and we also went to a really nice Vietnamese restaurant within walking distance. Also the Zoological Gardens underground station is within 5 mins walk - a major interchange for most of the underground lines. But the station area itself seems to be a bit of a dodgy place to hang around, particularly at night. Didn't see any trouble, but it felt a bit uncomfortable.
Breakfast was nice enough - a few choices of cereal, fruits, yogurts, cold meats / cheeses, breads, and a hot platter with bacon, scrambled and boiled eggs. Certainly enough to fill up on.
Like I said, it's been a good enough place to stay and I can't really complain, but if I were to come back I would like to try a different place - hence my "no" to the question about recommending to a friend.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC