Extremely well located (right in the old town!), everything can be done by walk. Imants' was always very responsive. Also very good value for money.
On the minus side, the flat is extremely basic (you can say, 3 beds + 1 bathroom), but this is fine if you don't intend to spend too much time there. Also to be noted, there were some foul odors coming from the bathroom and the water was cut for one night in the building (should be one-off, but still annoying).
Recommended if you are just looking for a cheap place to sleep in right in the heart of Riga.