Ease of Use
Daily usability is a factor that can not be over looked. You want a machine that is hassle-free to maximize your enjoyment. Look for simple dials and visual indicators. Easy access to steamer for cappuccino making requires a spout that is no more than five inches from the base of the counter. This involves having easy to read and well set out instructions with diagrams where necessary. It should graphically show how to assemble and disassemble the thing.

Easy Cleanup
Easily removable, dish-washer friendly parts are key in this dimension. You will also want easily accessible surfaces. A good espresso machine should have an easy to remove drip tray and, for larger models, grounds tray for ease of cleaning. It should also make it easy for you to clean the internals occasionally so that your espresso tastes fresh.

Strength controls
A little more elaborate than coffee maker controls, good espresso machines allow you to control how much water is used for each pull (and even the amount of grounds, for semi or fully automatic machines that dose automatically). By fine-tuning water and grounds, you can really produce the exact espresso you're looking for.

Visual Design
The look of your machine is an important part of the experience. Tastes abound and you should look around at various models before making your selection. Large and industrial looking is generally preferred. Shiny surfaces and glossy finish also lends some high scale feel.

Durability
Keep in mind that you will be subjecting your machine to repeated use, liquids, and temperature extremes. Examine the materials closely when choosing a machine. Metals are more durable than plastics. Examine all rubber parts to make sure there are no cracks.

Speed of Steamer
You want a machine that can quickly get the water sufficiently hot to get the steam going. Convenience is important here as one of the main reasons you will avoid using the machine is the time it may take to get your drink ready. You will want a machine that is ready to steam within thirty seconds.

Size and build
The capacity of an espresso machine should depend upon its intended use. A large reservoir for a single person machine means the water may become flat and de-oxygenated when you come to use it. Likewise, too small a reservoir for a group coffee machine means you will have to frequently refill it. Also, for a single user machine an automatic grinder and tampered may take up more space than you really need.

Price
The machines range from around $100 for a steam espresso machine up to $2,000 for a top of the line model. The type of machine will dictate the price. Decide what type you want before you purchase. Luckily, well-made espresso machines are workhorses and should last a few years.

Frothing Wand
A steam wand for frothing milk is a must-have if you plan on making lattes or cappuccinos. Simpler espresso machines have just a wand, but more elaborate machines will actually have a canister for milk.

Pod Compatible
The latest things in espresso making are pods. These little pre-packed discs of coffee grounds make espresso preparation a snap with no mess. Some of the newer models can take pods as well as regular loose coffee grounds.

Water Filter
Many espresso machines have built-in water filters to take out any chlorine or iron tastes from your tap water. A nice addition, but it also adds extra maintenance and cost (replacing the filters). Be sure the water filter is easily accessible for quick filter changes.

Integrated Bean Grinder
Not a typical feature, but you can buy espresso machines that have a built-in grinder. These types of machines will usually grind just enough coffee with each use, for the freshest brew around. You'll pay for this advanced feature though.