I've got a Gaggia Classic which I picked up second hand for £100 5 years ago. Paired with a GOOD grinder, it's not perfect, but if I'm on form I can get a top notch espresso out of it. Rancilio Silvia is the other good "decent beginner" machine.
Pro's over cheaper machines - all metal construction - big weighty brass portafilter to keep the pour warm before it hits the cup. Decent sized pump and boiler, three way solenoid valve to depressurize the brew head once the pour is done - stops the dreaded "portafilter sneeze" which sprays scalding hot coffee grounds all over the kitchen. There's room on top for warming cups. Steam capability is OK, but not as good as proper dual boiler or heat exchange machines.
Real world though, its the grinder and good fresh beans that make the difference. Spend there and you'll get a better cuppa.
Nespresso - based on the comments on previous STW threads, the missus and I went for a demo at Selfridges a few weeks back. Very easy and convenient, but the coffee produced was absolute, utter shite. Thin, watery and massively overextracted. We tried about 6 different varieties of capsule and it was the same all round. Really unimpressed. I think there's simply not enough coffee in the capsules to make a decent shot.