The Acer Liquid S1 is the first attempt at a phablet from the company. It features a 5.7 inch touch display, 8GB of internal storage which can be expanded through microSD, an 8 megapixel camera capable of 1080p HD video capture, a secondary camera for video calls and is powered by a 1.5GHz quad-core processor with 1GB of RAM.The Acer Liquid S1 is priced at 350 Euros ($460) which feels a bit pricey considering the weak chipset, subpar display and underwhelming camera performance. The Samsung Galaxy Mega 5.8 is an alternative worth considering, which also features two SIM slots and has almost identical dimensions and weight, with slightly larger battery and more RAM, but has a lower screen resolution.
Another alternative which offers good value for money is the Huawei Ascend Mate, which has a very generous 4050 mAh battery and great call quality, all at the same cost of the Liquid S1.
If you have an extra $100 to spend, you would likely be better off with the Samsung Galaxy Note II which has better performance and more bearable dimensions. You also get an inbuilt stylus, frequent software updates and much better resale value.
You can read a detailed review of the Acer Liquid S1 on PhoneArena.